Tutorial Guide AutoGrid 82 1 Advanced-Acrov5

Advanced Tutorials AutoGrid™ v8

- October 2007 -

NUMERICAL MECHANICS APPLICATIONS

Advanced Tutorials AutoGrid™ v8.c Documentation v8.c

NUMECA International 5, Avenue Franklin Roosevelt 1050 Brussels Belgium Tel: +32 2 647.83.11 Fax: +32 2 647.93.98 Web: http://www.numeca.com

NUMERICAL MECHANICS APPLICATIONS

Contents

TABLE OF CONTENT INTRODUCTION TUTORIAL 1: Meridional Effect 1-1 INTRODUCTION 1-1.1 Introduction 1-1.2 Prerequisites 1-1.3 Problem Description 1-1.4 Preparation 1-2 MESH GENERATION 1-2.1 Create Mesh Project 1-2.2 Load Geometry & Define Main Properties 1-2.3 Set Default Topology 1-2.4 Meridional Control 1-2.5 Blade-to-Blade Control 1-2.6 Meridional Effect Generation 1-2.7 3D Mesh Generation 1-2.8 3D Mesh Visualization 1-2.9 Check Boundary Conditions & Mesh Quality 1-2.10 Save Project 1-2.11 Periodic Full Non Matching Connection 1-2.12 Full Matching Connection

1-1 1-1 1-2 1-2 1-2 1-4 1-4 1-4 1-7 1-9 1-11 1-14 1-22 1-23 1-23 1-26 1-26 1-28

TUTORIAL 2: Non-Axisymmetric Hub/Shroud 2-1 INTRODUCTION 2-1.1 Introduction 2-1.2 Prerequisites 2-1.3 Problem Description 2-1.4 Preparation 2-2 MESH GENERATION 2-2.1 Create Mesh Project 2-2.2 Load Geometry & Define Main Properties 2-2.3 Set Default Topology 2-2.4 Meridional Control 2-2.5 Blade-to-Blade Control 2-2.6 3D Mesh Generation 2-2.7 3D Mesh Visualization 2-2.8 Check Boundary Conditions & Mesh Quality 2-2.9 Save Project

Tutorials

2-1 2-1 2-2 2-2 2-2 2-4 2-4 2-4 2-11 2-13 2-14 2-17 2-18 2-19 2-21

i

Contents

TUTORIAL 3: Bypass Configuration 3-1 INTRODUCTION 3-1.1 Introduction 3-1.2 Prerequisites 3-1.3 Problem Description 3-1.4 Preparation 3-2 MESH GENERATION 3-2.1 Create Mesh Project 3-2.2 Load Geometry & Define Main Properties 3-2.3 Set Default Topology 3-2.4 Meridional Control 3-2.5 Blade-to-Blade Control 3-2.6 3D Mesh Generation 3-2.7 3D Mesh Visualization 3-2.8 Check Boundary Conditions & Mesh Quality 3-2.9 Save Project

3-1 3-1 3-2 3-2 3-2 3-4 3-4 3-4 3-9 3-11 3-16 3-19 3-20 3-20 3-22

TUTORIAL 4: Tandem Row 4-1 INTRODUCTION 4-1.1 Introduction 4-1.2 Prerequisites 4-1.3 Problem Description 4-1.4 Preparation 4-2 MESH GENERATION 4-2.1 Create Mesh Project 4-2.2 Load Geometry & Define Main Properties 4-2.3 Set Default Topology 4-2.4 Meridional Control 4-2.5 Blade-to-Blade Control 4-2.6 3D Mesh Generation 4-2.7 3D Mesh Visualization 4-2.8 Check Boundary Conditions & Mesh Quality 4-2.9 Save Project

ii

4-1 4-1 4-2 4-2 4-2 4-4 4-4 4-4 4-7 4-8 4-9 4-12 4-13 4-14 4-16

Tutorials

Contents

TUTORIAL 5: Cascade Configuration 5-1 INTRODUCTION 5-1.1 Introduction 5-1.2 Prerequisites 5-1.3 Problem Description 5-1.4 Preparation 5-2 MESH GENERATION 5-2.1 Create Mesh Project 5-2.2 Load Geometry & Define Main Properties 5-2.3 Set Default Topology 5-2.4 Meridional Control 5-2.5 Blade-to-Blade Control 5-2.6 3D Mesh Generation 5-2.7 3D Mesh Visualization 5-2.8 Check Boundary Conditions & Mesh Quality 5-2.9 Save Project

5-1 5-1 5-2 5-2 5-2 5-4 5-4 5-4 5-9 5-10 5-11 5-15 5-15 5-16 5-18

TUTORIAL 6: Fin on Fan 6-1 INTRODUCTION 6-1.1 Introduction 6-1.2 Prerequisites 6-1.3 Problem Description 6-1.4 Preparation 6-2 MESH GENERATION 6-2.1 Create Mesh Project 6-2.2 Load Geometry & Define Main Properties 6-2.3 Set Default Topology 6-2.4 Meridional Control 6-2.5 Blade-to-Blade Control 6-2.6 3D Mesh Generation 6-2.7 3D Mesh Visualization 6-2.8 Check Boundary Conditions & Mesh Quality 6-2.9 Save Project

Tutorials

6-1 6-1 6-2 6-2 6-2 6-4 6-4 6-4 6-11 6-12 6-14 6-17 6-18 6-19 6-21

iii

Contents

TUTORIAL 7: 3D Technological Effect - Casing Treatment 7-1 INTRODUCTION 7-1.1 Introduction 7-1.2 Prerequisites 7-1.3 Problem Description 7-1.4 Preparation 7-2 MESH GENERATION 7-2.1 Open Existing Mesh Project 7-2.2 Adapt Mesh Project 7-2.3 3D Technological Effect Generation 7-2.4 Save Project

iv

7-1 7-1 7-2 7-2 7-2 7-4 7-4 7-4 7-7 7-17

Tutorials

What’s in This Guide ? This Tutorial Guide contains a number of advanced tutorials driving the user in AutoGrid™ v8 to mesh different internal turbomachinery configurations. In each tutorial, specific features related to mesh generation are demonstrated. Advanced Tutorials are detailed tutorials designed to introduce specific features available within AutoGrid™ v8. These tutorials provide explicit instructions for all steps of the mesh generation process. Advanced Tutorials do require as pre-requisite the knowledge of the mesh generation process presented in basic tutorials 1 to 7, and can be treated separately, in any order. They address different types of features available on both axial and centrifugal compressors, pumps and turbines.

Where to Find the Files Used in the Tutorials ? Each of the mesh generation starts from an existing geometry. The appropriate files (and any other relevant files used in the tutorial) are stored on AutoGrid™ v8 DVD-ROM, more precisely in the / DOC/_Tutorials/AutoGrid/_advanced directory.

How to Use this Guide ? Depending upon your familiarity with computational fluid dynamics and your interest in some particular configuration, you can use this tutorial guide in a variety of ways.

For the Beginner If you are beginning user of AutoGrid™, you should first read and solve basic tutorials 1 to 7, in order to familiarize yourself with the interface and basis of the mesh generation technique. You may then want to concentrate on a advanced tutorial that demonstrates features that you are going to resolve. For example, if you are planning to mesh a seal leakage, you should look at Advanced Tutorial 1.

For the Experienced User If you are an experienced user of AutoGrid™, you can read and/or solve the advanced tutorial(s) that demonstrate features that you are going to resolve. For example, if you plan to mesh a turbomachine presenting a non-axisymmetric hub, you should look at Advanced Tutorial 2.

Tutorials

1

Conventions Used in this Guide Several conventions are used in the tutorials to facilitate your learning process. Following a short introduction, each tutorial is divided into sections respectively related to the mesh generation steps from the geometry definition to the 3D mesh generation. Inputs required to execute the tutorials are restricted to the geometry, either in a ".geomTurbo" or CAD related format. The sequence of actions to be executed are described through a step-by-step approach, in the form of arabic numbers. Additional insight about some specific actions and/or features is frequently added to illustrate the tutorial further. This information is proposed for the purpose of clarity and completeness, and should not be executed. It appears in italicized type.

Contact NUMECA support team at +32-2-647.83.11 or send an e-mail to [email protected] for any question or information you may require. To allow NUMECA support to help you out within the shortest delays, please provide a detailed description of the observed behaviour and performed analysis.

2

Tutorials

TUTORIAL 1:

Meridional Effect

1-1

Introduction

1-1.1

Introduction

The resolution of computational fluid dynamics (CFD) problems involves three main steps:

• spatial discretization of the flow equations • flow computation • visualization of the results To answer these questions, NUMECA has developed a Flow INtegrated Environment for internal and Turbomachinery assimilations. Called FINE™/Turbo, the environment integrates the following tools:

• IGG™ is an Interactive Geometry modeler and Grid generator software, based on structured multi-block techniques

• AutoGrid™ is a three-dimensional Automated Grid generation software, dedicated to turbomachinery applications. Similarly to IGG™, it is based on structured multi-block techniques

• Euranus is a state-of-the-art multi-block flow solver, able to simulate Euler and Navier-Stokes equations in the laminar, transitional and turbulent regimes

• CFView™ is a highly interactive flow visualization and post-treatment software • FINE™ Graphical User Interface is a user-friendly environment that includes the different softwares. It integrates the concept of projects and allows the user to achieve complete simulations, going from the grid generation to the flow visualization, without the need of file manipulation A turbomachine is a device in which the energy is transferred either to or from a continuously flowing fluid by the dynamic action of one or more moving blade rows. It plays a major role in particular in aircraft, marine space (liquid rockets), land propulsion system but also in hydraulic, gas and steam turbines applications. It is also involved in industrial pipeline and processing equipment such as gas, petroleum and water pumping plants. Other applications can be related to heart-assist pumps, industrial compressors and refrigeration plants, among others. The turbomachinery field includes turbines, pumps, fans, compressors. A turbomachine is composed of several basic elements including the blade (also called vane if it is non-rotating), hub, and shroud. Several technological effects involving clearances, seal leakages and cooling holes among

Tutorials

1-1

Meridional Effect

Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of seal leakages in turbomachinery applications. It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • •

Read an existing geometrical file into AutoGrid™ v8; Control meridional flow paths and blade-to-blade mesh; Generate and control the mesh in the seal leakage; Control the quality of the mesh in the blade-to-blade and 3D mesh.

1-1.2

Prerequisites

This tutorial does not require any particular prerequisite but it is strongly recommended for beginners to perform the basic tutorials 1 to 7.

1-1.3

Problem Description

The problem to be considered is shown schematically here below (meridional view). The project consists in the mesh generation of a seal leakage on the top of the Aachen turbine rotor treated as an isolated axial-flow wheel.

1-1.4

Preparation

• Copy the files located in cdrom:\DOC\_Tutorials\AutoGrid\_advanced\Tutorial_1 to your working directory, where cdrom must be replaced by the name of your DVD-ROM.

• Start AutoGrid™ v8.x For LINUX and UNIX systems, you can access AutoGrid™ v8.x graphical user interface with the following command line igg -niversion 8x -print or igg -niversion autogrid8x -print

1-2

Tutorials

Introduction

Meridional Effect

For WINDOWS systems, you can access AutoGrid™ v8.x graphical user interface from the start menu going to /Programs/NUMECA software/fine8x/IGG or /Programs/NUMECA software/autogrid8x/IGG 4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the configuration presenting a seal leakage! AutoGrid™ v8 graphical user interface includes several windows that allow to visualize the geometry and mesh of the turbomachine simultaneously in the meridional, blade-to-blade and 3D view. The access to main menu and controls is proposed through a menu bar and a quick access pad, and is completed with a tool/icon bar. The execution of the different actions undertaken is summarized in the message box at the bottom of the interface.

Tutorials

1-3

Meridional Effect

1-2

Mesh Generation

Mesh Generation

A step by step approach is proposed in the following lines. It aims at driving you through the various steps that need to be executed from the creation of the mesh project to the validation of the final mesh quality.

1-2.1

Create Mesh Project

1.

Close the Open Turbo Project Wizard dialog box

2.

Go to menu File -> New Project

3.

Click yes to close the active project

4.

Choose the icon Start a New Project From Scratch The Open Turbo Project Wizard dialog box enables the user to retrieve a ".trb" file (with associated grid) including the data required to regenerate a mesh on an identical or similar geometry. In this tutorial, these data will be progressively introduced based on the geometry of the project case.

1-2.2

Load Geometry & Define Main Properties

5.

Click-left row1 in Rows Definition the current row

6.

Click-left in the meridional view

7.

Go to Geometry Definition

row 1 in the Quick Access Pad (QAP) to activate

Import and Link CAD

Graphic window opens, allowing geometry import. 8.

Click-left on File

9.

Select geometry.dat file from the file chooser

10. Define

Open...

the hub curve

• Click-left on the hub as it turns to yellow • Click-right and select Link to Hub Hub curve is displayed in the meridional view.

1-4

Tutorials

Mesh Generation

11.

Meridional Effect

Define the shroud curve

• Click-left on the shroud as it turns to yellow • Click-right and select Link to Shroud Shroud curve is displayed in the meridional view.

12. Define

the blade

• Click-left row1 in Rows Definition


the current row, if not done already

• Go to Geometry

Select

Surfaces

A message will prompt to select surfaces.

• Type key binding twice to select all surfaces (they turn to red or yellow) The binding key acts as a toggle, activating or de-activating all surfaces. The View/View Solid menu acts as a toggle and allows to visualize the surfaces that are active.

• Click-right twice to quit surfaces selection and select Link to Blade Blade is displayed in the meridional view.

Tutorials

1-5

Meridional Effect

Mesh Generation

13. Define

leading edge and trailing edge




• • • •

Click-left at blade leading edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Leading Edge Click-left at blade trailing edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Trailing Edge

Leading and trailing edges are displayed in the meridional view. When blade intersects hub and shroud, inlet and outlet are displayed in the meridional view.

1-6

Tutorials

Mesh Generation

Meridional Effect

14. Go

to File -> Exit

15. Click-left

on Rows Definition

16. Click-right

row 1 to activate row1

on row 1 to get the contextual menu and select Properties

17. Enter

the Periodicity (number of blades). Left-click inside the string input area and type <41>, press to confirm

18. Enter

<-3500> in Rotation Speed (rpm) This speed will be transferred to FINE™ graphical user interface and ease the input of boundary conditions later on. The sign of the rotational speed is positive (+) when the blade row is rotating in the positive θ direction, and negative otherwise.

19. Select

Rotor as a row type and Axial as a row orientation

The row type and row orientation settings are only information that will not impact or control the mesh generation process. 20. Close

1-2.3

the dialog box

Set Default Topology

21. Click-left 22. Select

on Rows Definition -> row 1 to activate the row, if not done already

Grid Level/Medium through Mesh Control in Quick Access Pad

23. Estimate

the width of the first cell at the wall:

The width of the first cell close to the wall must be selected with care since the quality of the flow solution will often depend upon the capture of the flow phenomena inside the boundary layers which develop along the solid walls. Depending upon the turbulence model selected, NUMECA recommends to locate the nearest grid point along the wall, at a distance that corresponds to

Tutorials

1-7

Meridional Effect

Mesh Generation

parietal coordinate y+ ranging from 1-5 (low Reynolds number models) or 3050 (high Reynolds number models). Assuming thermal effects must be modelled accurately, y+ can reach values as low as 0.1. The relation between the parietal coordinate y+ and width of the first cell close to the wall y is driven by the Blasius equation, expressed as follows for turbulent flows:

where: - ywall is the distance of the nearest grid point to the wall (in meter); - Vref is a reference velocity of the flow, for instance the inlet velocity (in m/s); - υ is the kinematic viscosity of the fluid (in m2/s), i.e. the dynamic viscosity divided by the density; - Lref is a reference length of the test case (in meter); - y+ is a non-dimensional value. In the present case, one can estimate that Vref=30 m/s; Lref=0.3m; υ=1.038e-5 m2/s Assuming one wishes to get y+ =1 at the wall, it comes that y = 1 x 10-5 m. Input the value of the Cell Width = <1e-5> in Row Mesh Control.

24. Select

(Re)set Default Topology in the toolbar and confirm (yes). This button will set the mesh topology to the default skin-like topology

1-8

Tutorials

Mesh Generation

Meridional Effect

The default skin-topology includes 5 blocks as follows: - the skin block is a O-mesh surrounding the blade - the inlet block is a H-mesh located upstream the leading edge - the outlet block is a H-mesh located downstream the trailing edge - the up block is a H-mesh located above the blade section - the down block is a H-mesh located under the blade section outlet block

up block

inlet block

1-2.4

Tutorials

skin block

Meridional Control

25. Move

• • • • • •

down block

inlet and outlet locations

Click-right on inlet curve when highlighted in yellow in the meridional view Select Properties Select Linear - Z constant, type <0.02>, press to confirm Click-right on outlet curve when highlighted in yellow in meridional view Select Properties Select Linear - Z constant, type <0.16>, press to confirm

1-9

Meridional Effect

Mesh Generation

The new inlet and outlet locations are displayed in the meridional view.

You can access the control points of the inlet/outlet line and modify their location by dragging the points. The exact coordinates of the control points can also be introduced with click-right on the control point; a dialog box appears, enabling the user to enter the point coordinates in (rz) mode. You can access the properties of the inlet/outlet line by click-right on control line when highlighted and selecting "Properties". The dialog box is divided in two main parts. The first part allows to specify the reference frame. When it is set to "Relative", the control points are relative to a row and their reference depends on the position of the control line. Either the control points are relative to the row inlet and its blade leading edge, either to the leading and trailing edge, or to the blade trailing edge and the row outlet. The second part of the dialog box allows to control the properties of the meridional control line namely the shape, the cell width, the streamwise index and the number of points in streamwise direction. 26. Select

(Re)set Default Topology in the toolbar and confirm (yes). This button will set the mesh topology to the default skin-like topology based on the new inlet/outlet locations

1-10

Tutorials

Mesh Generation

Meridional Effect

27. Go

to QAP Mesh Control

28. Modify

the number of flow path as <33>

flow paths if necessary through Mesh Control -> Row Mesh Control -> Flow Paths Control

29. Control

The Expert section allows the user to control the visualization, the shape and the parameters related to flow path smoothing. The meaning of these parameters is detailed in the user manual. The Manual Edition mode allows the user to control directly the block faces which are used to construct flow paths. Edges can be moved, segments can be created or modified and grid points distribution on segments can be controlled. More details can be found in the user manual. 30. Keep

data identical

31. Click

on Generate

32. Close

the dialog box

1-2.5

Blade-to-Blade Control

33. Click 34. Go

on Generate B2B

to Mesh Control

Tutorials

Row Mesh Control

B2B Mesh Topology Control

Topology

1-11

Meridional Effect

Mesh Generation

By default, non-matching connections are applied at periodic boundaries. Matching connections at periodic boundaries can be obtained by activating the Matching Periodicity check button. Press Re(set) Default Topology to regenerate the mesh in the blade-to-blade plane. In most cases, the presence of non-matching connections somehow improves the orthogonality in the overall mesh. This is especially true in highly staggered configurations. 35. Keep

Matching Periodicity deactivated and all other data identical In several turbomachinery types, the blades are highly staggered (Automatic High Staggered Blade Detection within AutoGrid™). If the solid angle at the inlet (outlet) of the machine becomes greater than 450 and if the location of the inlet (outlet) limits of the domain is close to the leading edge (trailing edge) of the blades, then the default topology is not suitable anymore since the cells located near the inlet (outlet) boundary become very skewed. To improve this unexpected behaviour, AutoGrid™ uses the High Staggered Blade Optimization.

36. Deactivate

Topology option

37. Go

to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view

38. Click-left

on the number of nodes, make the proper modification in the entry box and press to confirm the modification

The number of points specified is recommended to be 4xn + 1 (where n is an integer) to allow multigrid process on minimum 3 grid levels within FINE™. 39. Visualize

the result in blade-to-blade view after selecting Generate B2B to regenerate the flow paths and the mesh in blade-to-blade plane.

40. Deactivate 41. Close

Grid Points option

the dialog box.

to Mesh Control -> Active B2B Layer to specify the flow path (layer) on which the blade-to-blade mesh will be plotted in the blade-to-blade view

42. Go

1-12

Tutorials

Mesh Generation

Meridional Effect

By default, the active layer is the hub of the machine (Active Layer (%span) set to 0). The layer selected for visualization is defined in percentage of span, going from hub (0%) to shroud (100%). 43. Enter

for example <50> in order to visualize the mesh at 50% span

44. Select

Generate B2B to regenerate the blade-to-blade mesh on new specified layer in the blade-to-blade view Detailed analysis of mesh quality can be performed on Blade-to-Blade mesh after generation. Information on orthogonality, aspect ratio and expansion ratio can be outlined in this window using the Type pull-down menu and plotted in the blade-to-blade view on active layer selected in Mesh Control/ Active B2B Layer.

45. Check

for grid quality by clicking on

46. Select

quality criteria using the Type pull-down menu

47. Click-left

on Show chart to visualize the distribution of selected criteria in the form of an histogram. The histogram is drawn for each row

48. Click-left

on part of the histogram to plot the concerned cells in blade-to-blade view

49. Click-left

on More info button to obtain information about minimum and maximum values of the selected criteria

Click Left

50. Close

Tutorials

the dialog box

1-13

Meridional Effect

Mesh Generation

Control -> Row Mesh Control -> Optimization Control to adapt the mesh optimization parameters if necessary to enhance the quality of the mesh

51. Go to Mesh

Optimization is performed in the form of smoothing and is executed on each layer using multi-block elliptic techniques. The number of Optimization Steps represents the number of iterations performed with the elliptic smoother. By default, 100 iterations are applied. 52. Keep

default Optimization Steps and all other data identical

53. Close

the dialog box

1-2.6

Meridional Effect Generation

1-2.6.1 Configuration Control on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active the current row, if not done already

54. Click-left 55. Click

on the button Add ZR Effect to add a meridional effect in the configuration

1-2.6.2 Geometry Definition 56. Click-left on Rows Definition

-> zr techno effect 1 in the Quick Access Pad (QAP) if not

active already 57. Go

to Geometry Definition

Import and Link CAD

Graphic window opens, allowing geometry import. 58. Select

the curves defining the active meridional effect

• Click-left and -click-left on all the curve(s) as they turn to yellow

1-14

Tutorials

Mesh Generation

Meridional Effect

• Click-right and select Import Meridional

Curves defining the meridional effect are displayed in the meridional view.

Curves defining the meridional effects are specified in the ".geomTurbo" file using the basic curve format (see User Manual for more details). AutoGrid™ provides also geometrical features used to create the solid body of meridional effects interactively. New polylines and C-splines can be created using respectively the Geometry Control subpad and the Geometry menu in the meridional effect edition mode and the steps needed to create these polylines are stored in the ".trb" template file. 59. Click-left on Rows Definition

-> zr techno effect 1 in the Quick Access Pad (QAP) if not

active already

Tutorials

1-15

Meridional Effect

Mesh Generation

60. Click-right

on zr techno effect 1 to get the contextual menu and select Edit to access the meridional effect edition mode

When the meridional effect has several connections with the main blade channel, i.e. a seal leakage have a connection upstream the blade and a connection downstream the blade. In this case the mesh created inside the domain of the effect is divided into two part: one starting from the inlet and one starting from the outlet. At the middle part of the seal leakage, a separation line "rotor-stator" must be defined indicating the location of the division. At this line, defined in the edition mode, the two part of the mesh will be connected by a periodic connection if the connections with the main blade channel are related to the same row or a rotor/stator interface if the connections with the main blade channel are related to different rows. 61. Click

on Rotor-Stator Polyline in Geometry Control subpad to create a separation line

62. Click-left

on location (yellow spot on existing curve) where the "rotor-stator" polyline will

start 63. Click-left

on location (yellow spot on existing curve) where the "rotor-stator" polyline will

end 64. Click-right

1-16

to quit

Tutorials

Mesh Generation

Meridional Effect

No curves have to be added at the connection between the blade channel (hub or shroud) and the meridional effect. Automatically the hub and shroud curves will be used as limit of the meridional effect.

1-2.6.3 Topology Control The domain defining a technological effect must be filled by several structured 2D blocks. The block edges are mapped on the geometry. The Topology Control subpad provides the tools to create and control the blocks 65. Click-left

on Insert New Block icon in the Topology Control subpad to start to fill the

geometry 66. Click-left

to locate the first corner of the 2D block (yellow spot when attracted on existing

curve) 67. Click-left

to locate the opposite corner of the 2D block

68. Click-left

to create the 2D block

69. Click-left

on vertex (when highlighted in yellow) of the 2D block to move it when neces-

sary 70. Click-left 71. Repeat

to fix the new position of the vertex on the geometry

steps 69 and 70 for all vertices defining the 2D block

Click Left

The tool Detect Unmapped Edges in the Topology Default subpad allows to detect if the 2D blocks are well mapping the geometry. In addition, when the

Tutorials

1-17

Meridional Effect

Mesh Generation

vertex is highlighted, the curve on which it is mapped is mentioned in the info area at the bottom of the GUI.

72. Repeat

steps 65 to 71 in order to fill the geometry defining the meridional effect while respecting the following rules:

• the 2D blocks inserted in the meridional effect have to present edges fully and not partly connected to another block edge when connected

WRONG

CORRECT

• when the edge mapping is not performed as required, a vertex needs to be inserted

Undesired M apping

CORRECT

• a block connection must be established on the separation lines and the mapping of vertices respected (no orphan vertices)

separation line

WRONG

CORRECT separation line

1-18

Tutorials

Mesh Generation

Meridional Effect

• the 2D blocks should be connected to the rotor/stator polyline with a complete face

WRONG separation line

CORRECT separation line

• the 2D blocks should be connected to the shroud or hub with only one face

WRONG

CORRECT

SHROUD

SHROUD

The blocks can be deleted by click-left on the icon

.

73. Click

on Detect Unmapped Edges in the Topology Default subpad to control that all the blocks are well mapped

Tutorials

1-19

Meridional Effect

Mesh Generation

The tool Detect Unmapped Edges in the Topology Default subpad allows to highlight in green the edges that are not well mapped.

74. Click-right

to quit the Detect Unmapped Edges tool

1-2.6.4 Mesh Control The Topology Default subpad provides the tools to control the mesh of all the blocks filling the technological effect. 75. Keep

the Cell Width = <1e-5> (as the cell width imposed at step 23) and all other data identical

76. Deactivate

Periodic Full Non Matching

The Optimization Steps represents the number of iterations performed with the elliptic smoother. The Radial Expansion and Far Field Smoothing Steps are used for external cases as propeller or wind turbine applications. The Maximum Expansion Ratio and Cst Cells Percentage control the mesh that will be generated when using Default Topology. The Coarse Grid Level control the number of grid levels that will be available within FINE™. A minimum of 3 is recommended.

1-20

Tutorials

Mesh Generation

Meridional Effect

77. Click

on Default Topology in the Topology Default subpad to generate the mesh into the meridional effect (seal leakage)

separation line

If desired, the default topology can be modified by the user. When click-right on any edge, a popup menu allows to impose the number of points and the point distribution.

78. Click

on Detect Channel FNMB Connection in the Topology Default subpad to visualize the connections between the meridional effect and the channel

separation line

79. Click-right 80. Click

Tutorials

to quit the Detect Channel FNMB Connection tool

on Close Edition Mode

1-21

Meridional Effect

Mesh Generation

All the actions performed during an editing session are stored in the template file (".trb") and can be replayed on similar geometries.

1-2.7

3D Mesh Generation on Rows Definition -> row 1 and zr techno effect 1 in the Quick Access Pad (QAP) to active the current row, if not done already


on the icon Generate 3D and confirm the generation

Once 3D grid generation is completed, grid quality is performed and displayed. Minimum cells skewness, the maximum expansion ratio and aspect ratio are reported, among others. Data are available for the entire mesh separately for every entity (row, technological effect, bulb). Data related to grid quality report are automatically stored in a report file, once the project file is saved. 83. Close

1-22

the dialog box. This page can also be reopened by clicking on

Tutorials

Mesh Generation

1-2.8

Meridional Effect

3D Mesh Visualization on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active the current row, if not done already

84. Click-left

85. Click-right

on row 1 and select Properties to activate Default in order to plot the full tur-

bomachine

86. Click-right 87. Click-left

in 3D view; the Quick Access Pad (QAP) is modified

88. Click-right 89.

on row 1 and select Toggle 3D View to access the shaded blades in 3D view to get the contextual menu and activate Full View

Use View menu in QAP or View/Patch Viewer... menu to toggle edge or mesh

separation line

1-2.9

Tutorials

Check Boundary Conditions & Mesh Quality

1-23

Meridional Effect

Mesh Generation

90. Check

for boundary conditions by clicking on

91. Select

UND under Type pull-down menu and check that no patches are in the patch list still set with an undefined type

It is important to make sure that no undefined patches (UND) are present in the mesh. In that case, these can usually be removed by increasing the tolerance and launching the Search procedure. 92. Select

Full Non Matching/Define... to visualize the FNMB that are automatically created between the seal leakage (meridional effect) and the shroud of the channel

93. Close

1-24

both dialog boxes

Tutorials

Mesh Generation

Meridional Effect

94. Check

95. Click

for negative cells by clicking on

on Apply The computation of the negative volumes is performed first. Negative cells can be outlined in the mesh pushing View neg cells button. Beware that the visualization of negative cells can be memory consuming when a large number of cells must be displayed. It is then advised to first check the number of negative cells by pressing the Apply button. It is mandatory to remove all negative cells before the calculation can be started.

96. Check


Detailed analysis of mesh quality on 3D mesh (in blocks, at boundaries and at FNMB) can be performed only once the 3D mesh has been generated. Information on orthogonality, angular deviation, aspect ratio, expansion ratio and cell width can be outlined in this window using the Type pull-down menu. 97. Select


98. Click-left

on Show chart to visualize the distribution of selected criteria in the form of an histogram. The histogram is drawn per block (0 = all blocks)

99. Click-left

on part of the histogram to plot the concerned cells in the 3D view

Click Left

Tutorials

1-25

Meridional Effect

Mesh Generation

100.Click-left


101.Close

the dialog box

1-2.10 Save Project 102.

Go to File -> Save Project As to save mesh and template files The mesh files (7 files) contain the multiblock mesh topology, geometry and grid points and the boundary condition types: ".bcs", ".cgns", ".geom" (".xmt_txt"), ".igg", ".config" and ".qualityReport".The meaning of these files is detailed in the user manual. The template files (4 files) contain the parameters and the geometry needed to reproduced the mesh with AutoGrid™: ".geomTurbo" (".geomTurbo.xmt_txt"), ".trb" and ".info". The meaning of these files is detailed in the user manual.

1-2.11 Periodic Full Non Matching Connection AutoGrid™ allows to define a straight meridional effect (periodic boundaries of meridional effect at constant θ) by introducing periodic full non matching connection with repetition between the meridional effect and the channel. In most cases, this capability improves the orthogonality in the overall mesh. This is especially true in highly staggered configurations. on Rows Definition -> zr techno effect 1 in the Quick Access Pad (QAP) if not active already

103.Click-left

104.Click-right


1-26

Tutorials

Mesh Generation

Meridional Effect

105.Activate 106.Click

Periodic Full Non Matching


on Rows Definition -> row 1 and zr techno effect 1 in the Quick Access Pad (QAP) to active the current row, if not done already

107.Click-left 108.Click


Go to File -> Save Project As to save mesh and template files

109.

Tutorials

1-27

Meridional Effect

Mesh Generation

1-2.12 Full Matching Connection AutoGrid™ allows to define a full matching connection between the meridional effect and the channel by adding fixed control lines into the channel. This capability required in most cases more points in the mesh and an orthogonality that will not be improved in the overall mesh. This is especially true in highly staggered configurations. 110.Select

meridional view by click-left on it to active the view, if not done already

Mesh Control -> Row Mesh Control -> Add Z Constant Line to add z-constant lines to map the meridional effect

111.Select

112.Click-left

on shroud in the meridional view to add a z-constant line

113.Repeat step 112 three

times to map all the limits of the connections of the meridional effect

with the channel 114.Click-right

to quit the menu related to the creation of z-constant line

Ctrl Line 1 Ctrl Line 2


Click Left

Ctrl Line 1

You can access the control points of the z-constant line and modify their location by click-left and dragging the points. The exact coordinates of the control points can also be introduced with click-right on the control point; a dialog box appears, enabling the user to enter the point coordinates in (rz) mode. You can access the properties of the z-constant line by click-right on control line when highlighted and selecting "Properties". The dialog box is divided in two main parts. The first part allows to specify the reference frame. When it is set to "Relative", the control points are relative to a row and their reference depends on the position of the control line. Either the control points are relative to the row inlet and its blade leading edge, either to the leading and trailing edge, or to the blade trailing edge and the row outlet. The second part of

1-28

Tutorials

Mesh Generation

Meridional Effect

the dialog box allows to control the properties of the meridional control line namely the shape, the cell width, the streamwise index and the number of points in streamwise direction. 115.Click-right 116.

on first control line when highlighted in yellow

Select Properties

117.Activate 118.Set

Linear

the cell width to <1e-5>

Click Right

119.Click-left

on the three control lines and apply steps 117 and 118

120.Close dialog

box

on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active the current row, if not done already

121.Click-left 122.Select

(Re)set Default Topology in the toolbar and confirm (yes). This button will set the mesh topology to the default skin-like topology considering the four new control lines

In the blade-to-blade view, additional H-blocks are appearing.Furhermore, in some cases, the default topology may change from normal to high staggered (in this case the blade is high staggered at trailing edge).

Tutorials

1-29

Meridional Effect

Mesh Generation

Ctrl Line 1

Ctrl Line 2


In the edition mode of the meridional effect, the type connection can be controlled. on Rows Definition -> zr techno effect 1 in the Quick Access Pad (QAP) if not active already

123.Click-left

124.Click-right


125.Click

on Detect Channel Matching Connection in the Topology Default subpad to visualize the connections between the meridional effect and the channel

126.Click-right

to quit the Detect Channel Matching Connection tool

An additional control line needs to be added to define both matching connections because the connection of the meridional effect with the channel close to the trailing edge is defined by two blocks. 127.Click

on Solid Polyline in Geometry Control subpad to create a separation line

128.Click-left

on location (yellow spot on existing curve) where the "solid" polyline will start (at the connection between the two blocks)

1-30

Tutorials

Mesh Generation

Meridional Effect

129.Click-left

on location (yellow spot on existing curve) where the "solid" polyline will end (anywhere in the channel)

Click Left Click Left

This new solid polyline will allow the mapping of the new control line. 130.Click-right 131.Click

to quit


132.Select

meridional view by click-left on it to active the view, if not done already

Mesh Control -> Row Mesh Control -> Add Z Constant Line to add z-constant lines to map the meridional effect

133.Select

134.Click-left

on shroud in the meridional view to add a z-constant line at the connection with the channel close to the trailing edge (mapping on the new solid polyline)

135.Click-right 136.Select

Properties

137.Activate 138.Set

Tutorials

on last control line when highlighted in yellow

Linear

the cell width to <1e-5>

1-31

Meridional Effect

Mesh Generation

139.Close dialog

box


140.Click-left 141.Select

(Re)set Default Topology in the toolbar and confirm (yes). This button will set the mesh topology to the default skin-like topology considering the four new control lines

In the blade-to-blade view, one additional H-block is appearing between control lines 3 and 5.

Ctrl Line 1

Ctrl Line 2


Ctrl Line 4

In the edition mode of the meridional effect, the type connection can be controlled. on Rows Definition -> zr techno effect 1 in the Quick Access Pad (QAP) if not active already

142.Click-left

143.Click-right


144.Click

on Detect Channel Matching Connection in the Topology Default subpad to visualize the connections between the meridional effect and the channel

1-32

Tutorials

Mesh Generation

Meridional Effect

145.Click-right

to quit the Detect Channel Matching Connection tool

Both connections between the meridional effect and the channel are recognized as matching connections. 146.Click


on Rows Definition -> row 1 and zr techno effect 1 in the Quick Access Pad (QAP) to active the current row, if not done already

147.Click-left 148.Go

to QAP Mesh Control

149.Modify 150.Click

Tutorials



1-33

Meridional Effect

Mesh Generation

Full Non Matching

Full Matching

Go to File -> Save Project As to save mesh and template files

151.

1-34

Tutorials

TUTORIAL 2:

Non-Axisymmetric Hub/Shroud

2-1

Introduction

2-1.1

Introduction







Tutorials

2-1


Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of a turbomachine presenting a hub and/or shroud non-axisymmetric. It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • • •

Read an existing geometrical file into AutoGrid™ v8; Control meridional flow paths when hub/shroud non-axisymmetric; Control blade-to-blade mesh; Control the mesh projection on the hub/shroud non-axisymmetric; Control the quality of the mesh in the blade-to-blade and 3D mesh.

2-1.2

Prerequisites


2-1.3

Problem Description

The problem to be considered is shown schematically here below. The project consists in the mesh generation of a Aachen turbine stator (treated as an isolated axial-flow wheel) when presenting a non-axisymmetric hub.

2-1.4

Preparation



2-2

Tutorials

Introduction


For WINDOWS systems, you can access AutoGrid™ v8.x graphical user interface from the start menu going to /Programs/NUMECA software/fine8x/IGG or /Programs/NUMECA software/autogrid8x/IGG 4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the non-axisymmetric configuration! AutoGrid™ v8 graphical user interface includes several windows that allow to visualize the geometry and mesh of the turbomachine simultaneously in the meridional, blade-to-blade and 3D view. The access to main menu and controls is proposed through a menu bar and a quick access pad, and is completed with a tool/icon bar. The execution of the different actions undertaken is summarized in the message box at the bottom of the interface.

Tutorials

2-3


2-2

Mesh Generation

Mesh Generation


2-2.1

Create Mesh Project

1.

Close the Open Turbo Project Wizard dialog box

2.


3.


4.

Choose the icon Start a New Project From Scratch The Open Turbo Project Wizard dialog box enables the user to retrieve a ".trb" file (with associated grid) including the data required to regenerate a mesh on an identical or similar geometry. In this tutorial, these data will be progressively introduced based on the geometry of the project case.

2-2.2


5.


6.


7.



Import and Link CAD


Click-left on File

9.


10. Define

Open...

the hub curve

• Click-left on the hub as it turns to yellow • Click-right and select Link to Hub Hub curve is displayed in the meridional view.

2-4

Tutorials

Mesh Generation

11.


Define the shroud curve

• Click-left on the shroud as it turns to yellow • Click-right and select Link to Shroud Shroud curve is displayed in the meridional view.

In addition to the axisymmetric hub and shroud curves defining the meridional domain, 3D surfaces defining the non-axisymmetric end walls must be defined. These can be directly specified in the ".geomTurbo" file (more details in User Manual) or imported through the Import CAD window. 12. Define

the non-axisymmetric surface defining the hub

• Click-left on the surface defining the hub when highlighted in blue, it turns to yellow • Click-right and select Link Non Axi to Hub

Click Left

Tutorials

2-5


Mesh Generation

The 3D surfaces defining the non-axisymmetric end walls must present the same peridiocity as the row. 13. Define

the blade




• Click-left on first surface defining the blade when highlighted in blue (it turns to red or yellow)

• Click-middle to select the second surface defining the blade • - click-left on second surface defining the blade when highlighted in blue (it turns to red or yellow)

Click Left

Click Middle Click Left

The View/View Solid menu acts as a toggle and allows to visualize the surfaces that are active.

• Click-right and select Link to Blade Blade is displayed in the meridional view.

2-6

Tutorials

Mesh Generation


14. Define





• • • •

Click-left at blade leading edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Leading Edge Click-left at blade trailing edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Trailing Edge Leading and trailing edges are displayed in the meridional view. When blade intersect hub and shroud, inlet and outlet are displayed in the meridional view.

15. Go

to File -> Exit

16. Click-left

on Rows Definition

17. Click-right

row 1 to activate row1

on row 1 to get the contextual menu and select Properties

18. Enter

the Periodicity (number of blades). Left-click inside the string input area and type <36>, press to confirm

19. Enter

<0> in Rotation Speed (rpm) This speed will be transferred to FINE™ graphical user interface and ease the input of boundary conditions later on. The sign of the rotational speed is positive (+) when the blade row is rotating in the positive θ direction, and negative otherwise.

20. Select

Stator as a row type and Axial as a row orientation

The row type and row orientation settings are only information that will not impact or control the mesh generation process.

Tutorials

2-7


Mesh Generation

The non axisymmetric end walls generation is controlled into the Row Properties dialog box.

21. Keep

Non-Axisymmetric Hub active The "Non-Axisymmetric Hub & Shroud" is used to enable or disabled the mesh adaptation on the specified non axisymmetric surfaces.

22. Keep

Projection Along Face Normal active by default When the non axisymmetric surface is not intersecting the axisymmetric mesh: The "Projection Along Face Normal" is projecting the mesh on the surface using the hub or shroud normal face directions. Therefore, as on the connected face boundary the computed normal can be different for both faces, the matching connection may become non-matching. The "Projection Along Grid Line" is projecting the mesh on the surface using the spanwise grid line direction to compute the normal. This approach allows to avoid non-matching connections.

23. Keep

2-8

Repair Non-projected Points active by default

Tutorials

Mesh Generation


The "Repair Non-projected Points" allows to correct non-well projected points (i.e. when the mesh points on boundaries are close to hub or shroud surface limits). 24. Set

the Geometry Repetition to <2> The non-axisymmetric 3D surfaces must cover all the hub or shroud blade to blade domain of the axisymmetric mesh. If the specified surfaces does not cover the entire domain as shown in the next figure, the Geometry Repetition option allows the user to repeat the entered surfaces by rotation on both sides.

The "Display Non-Axisymmetric Hub & Shroud" is used to display the nonaxisymmetric surfaces in the 3D view 25. Close

the dialog box At the end of the 3D blade row generation, the mesh adaptation on the nonaxisymmetric surfaces is performed automatically. The axisymmetric mesh is adapted by hub to shroud grid points redistribution along the curve obtained by intersecting the surfaces with the hub to shroud grid lines. It is thus recommended to generate a axisymmetric mesh covering completely the nonaxisymmetric surfaces.

26. Click-left 27. Go

in the meridional view



Import and Link CAD

on the surface defining the hub when highlighted in blue, it turns to yellow

Geometry/Modify Surface/Add uv Curves

30. Click-left

on the surface in order to define new curves plotting the non-axisymmetry appearing on the hub

31. Click-left

on the new curve until it turns yellow

32. Click-right

Click Left

Tutorials

and select Import Meridional

Click Left

2-9


Mesh Generation

The limit of the non-axisymmetric hub is appearing in the meridional view.

33. Move

hub curve to create a channel including the non-axisymmetric effect

• Click-left in the meridional view • Go to Geometry Definition Edit Hub to visualize the vertices defining the hub • Click-left on vertex (at inlet) and define its new position in the keyboard input area in ZRTH coordinates where Z is the Zinlet and R is lower than the Rmin of the non-axisymmetric effect: <-0.03 0.242 0>

• Click-left on vertex (at outlet) and define its new position in the keyboard input area in ZRTH coordinates where Z is the Zoutlet and R is lower than the Rmin of the non-axisymmetric effect: <0.054737609091 0.242 0>

• Click-right to regenerate the channel

The hub appears as a dashed green line because it is no more mapping on a curve.

2-10

Tutorials

Mesh Generation


The blade is no more intersecting the new hub. The blade needs to be extended. 34. Click-left

on Rows Definition

35. Click-right 36. Select

row 1

Blades

Main Blade

on Main Blade to get the contextual menu and select Expand Geometry

Hub treatment/expand

• Set Cut offset to <0.001> • Set Extension offset to <0.001>

• Apply to extend the blade MERIDIONAL

Cut Offset = 0.001 [m] ≈ 0.0003 [m]

Expand Offset = 0.001 [m]

The tool Geometry/Distance allows to measure the distance between two points in the active view.

2-2.3



Tutorials

on Rows Definition -> row 1 to activate the row, if not done already


2-11


39. Estimate

Mesh Generation


The width of the first cell close to the wall must be selected with care since the quality of the flow solution will often depend upon the capture of the flow phenomena inside the boundary layers which develop along the solid walls. Depending upon the turbulence model selected, NUMECA recommends to locate the nearest grid point along the wall, at a distance that corresponds to parietal coordinate y+ ranging from 1-5 (low Reynolds number models) or 3050 (high Reynolds number models). Assuming thermal effects must be modelled accurately, y+ can reach values as low as 0.1. The relation between the parietal coordinate y+ and width of the first cell close to the wall y is driven by the Blasius equation, expressed as follows for turbulent flows:

where: - ywall is the distance of the nearest grid point to the wall (in meter); - Vref is a reference velocity of the flow, for instance the inlet velocity (in m/s); - υ is the kinematic viscosity of the fluid (in m2/s), i.e. the dynamic viscosity divided by the density; - Lref is a reference length of the test case (in meter); - y+ is a non-dimensional value. In the present case, one can estimate that Vref=30 m/s, Lref=0.3m and υ=1.038e-5 m2/s Assuming one wishes to get y+ =1 at the wall, it comes that y = 1 x 10-5 m. Input the value of the Cell Width = <1e-5> in Row Mesh Control.

40. Select


2-12

Tutorials

Mesh Generation


The flow paths are covering the non-axisymmetric hub.

The default skin-topology includes 5 blocks as follows: - the skin block is a O-mesh surrounding the blade - the inlet block is a H-mesh located upstream the leading edge - the outlet block is a H-mesh located downstream the trailing edge - the up block is a H-mesh located above the blade section - the down block is a H-mesh located under the blade section up block

inlet block outlet block skin block down block

2-2.4 41.

Meridional Control Go to QAP Mesh Control

42. Modify



43. Control

Tutorials

2-13


Mesh Generation

The Expert section allows the user to control the visualization, the shape and the parameters related to flow path smoothing. The meaning of these parameters is detailed in the user manual. The Manual Edition mode allows the user to control directly the block faces which are used to construct flow paths. Edges can be moved, segments can be created or modified and grid points distribution on segments can be controlled. More details can be found in the user manual. 44. Keep

data identical

45. Click

on Generate

46. Close

the dialog box

2-2.5


47. Click 48. Go

on Generate B2B

to Mesh Control

2-14

Row Mesh Control


Topology

Tutorials

Mesh Generation




50. Deactivate

Topology option

51. Go

to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view

52. Click-left

on the number of nodes, make the proper modification in the entry box and press to confirm the modification




Grid Points option

the dialog box.


56. Go

Tutorials

2-15


Mesh Generation

By default, the active layer is the hub of the machine (Active Layer (%span) set to 0). The layer selected for visualization is defined in percentage of span, going from hub (0%) to shroud (100%). 57. Enter


58. Select


59. Check


60. Select


61. Click-left


62. Click-left

on part of the histogram to plot the concerned cells in blade-to-blade view

63. Click-left


Click Left

64. Close

the dialog box

Control -> Row Mesh Control -> Optimization Control to adapt the mesh optimization parameters if necessary to enhance the quality of the mesh

65. Go to Mesh

Optimization is performed in the form of smoothing and is executed on each layer using multi-block elliptic techniques. The number of Optimization Steps represents the number of iterations performed with the elliptic smoother. By default, 100 iterations are applied.

2-16

Tutorials

Mesh Generation


66. Keep


67. Close

the dialog box

2-2.6

3D Mesh Generation on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active the current row, if not done already



At the end of the 3D blade row generation, the mesh adaptation on the nonaxisymmetric hub is performed automatically. The axisymmetric mesh is adapted by hub to shroud grid points redistribution along the curve obtain by intersecting the surfaces with the hub to shroud grid lines.

Once 3D grid generation is completed, grid quality is performed and displayed. Minimum cells skewness, the maximum expansion ratio and aspect ratio are reported, among others. Data are available for the entire mesh separately for every entity (row, technological effect, bulb). Data related to grid quality report are automatically stored in a report file, once the project file is saved.

Tutorials

2-17


70. Close

2-2.7

Mesh Generation


3D Mesh Visualization on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active the current row, if not done already

71. Click-left

72. Click-right

on row 1 and select Properties to activate Default in order to plot the full tur-

bomachine

73. Click-right 74. Click-left


75. Click-right 76.

on row 1 and select Toggle 3D View to access the shaded blades in 3D view to get the contextual menu and activate Full View


Non-Axisymmetric Hub

Non-Axisymmetric Hub

2-18

Tutorials

Mesh Generation

2-2.8



77. Check


78. Select


It is important to make sure that no undefined patches (UND) are present in the mesh. In that case, these can usually be removed by increasing the tolerance and launching the Search procedure.

Tutorials

79. Close

dialog box

80. Check


2-19


81. Click

Mesh Generation


82. Check




84. Click-left


85. Click-left


Click Left

86. Click-left


87. Close

2-20

the dialog box

Tutorials

Mesh Generation

2-2.9 88.


Save Project Go to File -> Save Project As to save mesh and template files The mesh files (7 files) contain the multiblock mesh topology, geometry and grid points and the boundary condition types: ".bcs", ".cgns", ".geom" (".xmt_txt"), ".igg", ".config" and ".qualityReport".The meaning of these files is detailed in the user manual. The template files (4 files) contain the parameters and the geometry needed to reproduced the mesh with AutoGrid™: ".geomTurbo" (".geomTurbo.xmt_txt"), ".trb" and ".info". The meaning of these files is detailed in the user manual.

Tutorials

2-21


2-22

Mesh Generation

Tutorials

TUTORIAL 3:

Bypass Configuration

3-1

Introduction

3-1.1

Introduction







Tutorials

3-1


Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of bypass turbomachine applications (airplane engine). It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • •

3-1.2

Read an existing geometrical file into AutoGrid™ v8; Control meridional flow paths especially at the nozzle; Control the blade-to-blade mesh; Control the quality of the mesh in the blade-to-blade and 3D mesh.

Prerequisites


3-1.3

Problem Description

The problem to be considered is shown schematically here below (meridional view). The project consists in the mesh generation of a bypass configuration (part of an airplane engine). The configuration is composed by a fan in front of the nozzle, three rows in the down bypass and one row in the up bypass

3-1.4

Preparation


• Start AutoGrid™ v8.x

3-2

Tutorials

Introduction


For LINUX and UNIX systems, you can access AutoGrid™ v8.x graphical user interface with the following command line igg -niversion 8x -print or igg -niversion autogrid8x -print For WINDOWS systems, you can access AutoGrid™ v8.x graphical user interface from the start menu going to /Programs/NUMECA software/fine8x/IGG or /Programs/NUMECA software/autogrid8x/IGG

4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the bypass configuration!

Tutorials

3-3


Mesh Generation

AutoGrid™ v8 graphical user interface includes several windows that allow to visualize the geometry and mesh of the turbomachine simultaneously in the meridional, blade-to-blade and 3D view. The access to main menu and controls is proposed through a menu bar and a quick access pad, and is completed with a tool/icon bar. The execution of the different actions undertaken is summarized in the message box at the bottom of the interface.

3-2

Mesh Generation


3-2.1 1.

Create Mesh Project Close the Open Turbo Project Wizard dialog box The Open Turbo Project Wizard dialog box enables the user to retrieve a ".trb" file (with associated grid) including the data required to regenerate a mesh on an identical or similar geometry. In this tutorial, these data will be progressively introduced based on the geometry of the project case.

2.


3.


4.

Choose the icon Initialize a New Project from a geomTurbo File

3-2.2 5.

Load Geometry & Define Main Properties Locate and select bypass.geomTurbo (geometry defined in [Millimeter]) in the dialog box and click Open The ".geomTurbo" file format is structured in three main blocks: the header, the channel and the row(s) definitions.

3-4

Tutorials

Mesh Generation


The channel format contains the definition of the turbomachinery meridional contour (hub, shroud and nozzle). It is composed by curves defined by a set of points. The ".geomTurbo" file must contain two channel curves named respectively "hub" and "shroud". In addition when meshing a bypass configuration, the nozzle must be defined.

shroud

… …

OUTLET

INLET hub

…

nozzle

The nozzle must be defined from the outlet down bypass to the outlet up bypass

The row definition contains the geometry of a complete row. The blade and splitter are defined by the pressure and the suction side surfaces identified by the keywords "pressure" and "suction". Both surfaces are specified by a set of cross sections of the blade at several spanwise location from hub to shroud. Each section is defined by a set of points from leading to trailing edge.

Row defined in front of nozzle

Row defined in up bypass

Row defined in down bypass

Tutorials

3-5


Mesh Generation

The geometry can also be imported through a graphic window (Geometry Import and Link CAD) when defining a new project from Definition scratch with bypass. When click-right in the graphic window, a pop-up menu allows the user to define the nozzle in addition of the hub and shroud. In addition row on nozzle and in up/down bypass can be added in the configuration.

Warning may prompt if one of the rows is not intersecting the hub and/or he shroud.

The warning inform the user that the row 3 needs to be extended to intersect the hub.

6.

Click-left on Ok

7.

Click-left on Rows Definition

8.

Click-right on Main Blade to get the contextual menu and select Expand Geometry

9.

Select Hub treatment/expand

row 3

Blades

Main Blade

• Set Expansion Factor to <0.02>

3-6

Tutorials

Mesh Generation


• Apply to extend the blade

10. Click-left 11.

on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active it

Click-right on row 1 and select Properties in the pop-up menu

12. Enter 13. Enter

the Periodicity (number of blades) to <18> <500> in Rotation Speed (rpm) The speed will be transferred to FINE™ graphical user interface and ease the input of boundary conditions later on. The sign of the rotational speed is positive (+) when the blade row is rotating in the positive θ direction, and negative otherwise

14. Select


The row type and row orientation settings are only information that will not impact or control the mesh generation process. 15. Activate

Default in order to plot the full turbomachine in 3D view when selecting View/ toggle 3D Solid View

16. Execute

the same operations for the elements row2, row3, row4 and row5, defined respectively by the following parameters as <77>-<0>-Stator-Axial, <119>-<0>-Stator-Axial, <127>-<500>-Rotor-Axial and <117>-<0>-Stator-Axial (it is not necessary to close the dialog box each time)

17. Close

Tutorials

the dialog box

3-7


Mesh Generation

18. Click-left

on Rows Definition -> row 1

19. Click-right 20. Keep

21. Define

Width At Trailing Edge = <6.0> [Millimeters]

22. Click-left

on Rows Definition -> row 3 and row 5

23. Click-right

and select Define Hub Gap in the pop-up menu

24. Define

Width At Leading Edge = <1.0> [Millimeters]

25. Define


26. Click-left

3-8

and select Define Shroud Gap in the pop-up menu



Tutorials

Mesh Generation


27. Click-right


28. Define


29. Define


The width at leading/trailing edge allows to specify the size of the gap respectively at the leading and trailing edge of the blade. The gap curve is then constructed as a linear offset of the hub (or the shroud) according to these values. 30. Set

the scaling factor

• Go to Geometry Definition Units • Change the units to Millimeters

The "units" of the imported geometry must be changed to impose a scaling factor and a corresponding tolerance that will ensure correct treatment during the grid generation when computing for example the intersection. If not necessary, we recommend to keep the default settings (Scale Factor set to 1) 31. Click-left

on Select All Rows

32. Select

toggle 3D Solid View in the View menu to access the shaded blades in 3D view

33. Select

toggle 3D Solid View in the View menu to remove the shaded blades in 3D view

3-2.3



on Select All Rows


36. Estimate


The width of the first cell close to the wall must be selected with care since the quality of the flow solution will often depend upon the capture of the flow phenomena inside the boundary layers which develop along the solid walls. Depending upon the turbulence model selected, NUMECA recommends to locate the nearest grid point along the wall, at a distance that corresponds to

Tutorials

3-9


Mesh Generation

parietal coordinate y+ ranging from 1-5 (low Reynolds number models) or 3050 (high Reynolds number models). Assuming thermal effects must be modelled accurately, y+ can reach values as low as 0.1. The relation between the parietal coordinate y+ and width of the first cell close to the wall y is driven by the Blasius equation, expressed as follows for turbulent flows:

where: - ywall is the distance of the nearest grid point to the wall (in meter); - Vref is a reference velocity of the flow, for instance the inlet velocity (in m/s); - υ is the kinematic viscosity of the fluid (in m2/s), i.e. the dynamic viscosity divided by the density; - Lref is a reference length of the test case (in meter); - y+ is a non-dimensional value. Input the value of the Cell Width = <1e-2> [Millimeters] in Row Mesh Control.

37. Select


The default skin-topology includes 5 blocks as follows: - the skin block is a O-mesh surrounding the blade

3-10

Tutorials

Mesh Generation


- the inlet block is a H-mesh located upstream the leading edge - the outlet block is a H-mesh located downstream the trailing edge - the up block is a H-mesh located above the blade section - the down block is a H-mesh located under the blade section

3-2.4

Meridional Control When overlapping detected in the flow paths, a warning is appearing at the bottom of the graphical user interface. In addition, the expansion ratio is plotted in the message box.

38. Check

quality of the flow paths

• Click-left in meridional view to activate it (red border) • Click-left on • Select quality criteria using the Type pull-down menu • Click-left on Show chart to visualize the distribution of selected criteria in the form of an histogram. The histogram is drawn for each row

• Click-left on part of the histogram to plot the concerned cells in the meridional view • Click-left on More info button to obtain information about minimum and maximum values of the selected criteria

• Close dialog box

Click Left

39. Control

bypass and nozzle points distributions

• Click-left on Select All Rows • Click-left on Mesh Control -> Row Mesh Control -> Flow Paths Control -> Expert • Deactivate View Flow Path to plot the grid used to generate the flow paths

Tutorials

3-11


Mesh Generation


3-2.4.1 Bypass - Nozzle Control • Click-left on • Click-left on double arrow when highlighted in red, type <0.6903832> to control the points distribution on nozzle and to remove overlapping cells

• Click-left on Select All Rows • Click-left on Generate Flow Paths

Click Left

• Click-left on thickness (0.3%), type <5> to increase the thickness of the C-block covering the nozzle


3-12

Tutorials

Mesh Generation


Click Left

Click-left on the number of nodes, make the proper modification in the entry box and press to confirm the modification. Nozzle flow paths index and nozzle cell width can also be imposed. H-topology on nozzle is adapted for bypass configuration presenting a sharp nozzle.

40. Adapt

• • • •

control lines close to nozzle

Click-left on control line defining the nozzle topology when highlighted in yellow Click-left on control point defining the control line Move control point at desired location Click-left on control point to validate its new location

Click Left

The exact coordinates of the control points can also be introduced with clickright on the control point; a dialog box appears, enabling the user to enter the point coordinates in (rz) mode.

• Click-right on control line defining the nozzle topology when highlighted in yellow • Select Properties • Set the Cell width respectively to <1.0> and <1.0> The same cell width has to be imposed on both control lines defining the nozzle.

Tutorials

3-13


Mesh Generation

• Set the streamwise number of points (Streamwise Npts) respectively to <17> and <13>

1.0


3-2.4.2 Copy/Paste Flow Paths Distribution • • • •

Click-right on the outlet of the up bypass when highlighted in yellow Select Copy Left Distribution Click-right on the rotor/stator of the up bypass when highlighted in yellow Select Paste Right Distribution

C --> R

Copy/Paste are used to copy a distribution from a rotor/stator to another one or to a meridional control line. Merge is used to compute a common distribution from the left and right distributions at a rotor/stator. It is created for rotor/stators where the left row has a hub gap and the right row a shroud gap (or the opposite). Clear is used to clean copy/merge operations on selected control line.


3-14

Tutorials

Mesh Generation


Along the down bypass, automatic copy/paste and merge flow paths distributions are performed.

M

M

C --> R

C --> L

3-2.4.3 Bulb Control The configuration is presenting a hub defined with a control point at R=0. A bulb is automatically detected and flow paths controls are added. 41. Adapt

• • • •

control line close to the bulb

Click-left on control line when highlighted in yellow Click-left on control point defining the control line Move control point at desired location Click-left on control point to validate its new location

Click Left

• Click-left on Select All Rows • Click-left on Generate Flow Paths 42. Adapt

flow paths distribution in bulb

• Click-left on • Deactivate Singular line to impose a butterfly topology in the bulb Three topologies are available for bulbs: sharp (H-mesh), rounded (C-mesh) or radial. With C mesh, the zero radius area can be meshed with a singular line or a butterfly topology. Butterfly topology

Singular line

Tutorials

3-15


Mesh Generation

Click-left on the number of nodes, make the proper modification in the entry box and press to confirm the modification.

• Close dialog box • Click-left on Select All Rows • Click-left on Generate Flow Paths 43. Check

3-2.5

quality of the flow paths as presented in step 38


44. Click

on Generate B2B

row 4

row 1

row 3

row 5

When plotting all rows on hub (active layer set 0% by default), the row 2 is not appearing in the blade-to-blade view because it is not intersecting the hub. To check the mesh on row 2, an active layer intersecting the row 2 should be selected.

3-16

Tutorials

Mesh Generation


45. Go

to Mesh Control

Row Mesh Control


Topology



47. Deactivate

Topology option

48. Go

to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view if necessary

49. Click-left on

the number of nodes, make the proper modification in the entry box and press to confirm the modification

The number of points specified is recommended to be 4xn + 1 (where n is an integer) to allow multigrid process on minimum 3 grid levels within FINE™.

Tutorials

3-17


Mesh Generation

50. Visualize



Grid Points option

the dialog box.


53. Go

By default, the active layer is the hub of the machine (Active Layer (%span) set to 0). The layer selected for visualization is defined in percentage of span, going from hub (0%) to shroud (100%) and is applied on active row(s). 54. Click-left 55. Enter

on Select All Rows


56. Select


57. Check


58. Select


59. Click-left


60. Click-left

on part of the histogram to plot the concerned cells in the blade-to-blade view

61. Click-left on

More info button to obtain information about minimum and maximum values of the selected criteria

Click Left

3-18

Tutorials

Mesh Generation


62. Close

the dialog box

63. Go to Mesh Control ->

Row Mesh Control -> Optimization Control to adapt the mesh optimization parameters if necessary to enhance the quality of the mesh



65. Close

the dialog box

3-2.6

3D Mesh Generation


Tutorials

on Select All Rows


3-19


Mesh Generation


3-2.7


3D Mesh Visualization


on Select All Rows

View/toggle 3D Solid View to access the shaded blades in 3D view

71. Click-left


72. Click-right 73.

3-2.8



74. Check

3-20

to get the contextual menu and activate Full View


Tutorials

Mesh Generation


75. Select


It is important to make sure that no undefined patches (UND) are present in the mesh. In that case, these can usually be removed by increasing the tolerance and launching the Search procedure. 76. Close

the dialog box

77. Check


78. Click


Tutorials

79. Close

the dialog box

80. Check


3-21


Mesh Generation



82. Click-left


83. Click-left


Click Left

84. Click-left on


85. Close

3-2.9 86.

the dialog box


3-22

Tutorials

TUTORIAL 4:

Tandem Row

4-1

Introduction

4-1.1

Introduction







Tutorials

4-1

Tandem Row

Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of tandem row configuration. It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • •

4-1.2

Read an existing geometrical file into AutoGrid™ v8; Define a tandem row; Control the blade-to-blade mesh; Control the quality of the mesh in the blade-to-blade and 3D mesh.

Prerequisites


4-1.3

Problem Description

The problem to be considered is shown schematically here below (meridional view). The project consists in the mesh generation of a tandem row configuration (part of an airplane engine). The configuration consists in a single row composed by a main blade and a splitter without overlap in the streamwise direction.

4-1.4

Preparation



4-2

Tutorials

Introduction

Tandem Row


4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the tandem configuration!

Tutorials

4-3

Tandem Row

Mesh Generation


4-2

Mesh Generation


4-2.1 1.


2.


3.


4.

Choose the icon Initialize a New Project from a geomTurbo File

4-2.2 5.

Load Geometry & Define Main Properties Locate and select tandem.geomTurbo (geometry defined in [Millimeter]) in the dialog box and click Open The ".geomTurbo" file format is structured in three main blocks: the header, the channel and the row(s) definitions. The channel format contains the definition of the turbomachinery meridional contour (hub and shroud). It is composed by curves defined by a set of points. The ".geomTurbo" file must contain two channel curves named respectively "hub" and "shroud".

4-4

Tutorials

Mesh Generation

Tandem Row

The tandem configuration is defined by a single row composed by a main blade and a splitter downstream the main blade without overlap in the streamwise direction. The row definition contains the geometry of a complete row. The main blade and splitter are defined by the pressure and the suction side surfaces identified by the keywords "pressure" and "suction". Both surfaces are specified by a set of cross sections of the blade at several spanwise location from hub to shroud. Each section is defined by a set of points from leading to trailing edge.

INLET

OUTLET

Main Blade

Splitter 1

The geometry can also be imported through a graphic window (Geometry Definition Import and Link CAD) when defining a new project from scratch. When click-right in the graphic window, a pop-up menu allows the user to define the hub, shroud and to link the surfaces, trailing and leading edge curves to the selected blade in the Rows Definition (Main Blade or Splitter 1). When click-right on row 1 in Rows Definition, a menu allows the user to add a blade (splitter) in the selected row;

Tutorials

6.

Click-left on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active it

7.

Click-right on row 1 and select Properties in the pop-up menu

8.

Keep the Periodicity (number of blades) to <75>

9.

Keep <500> in Rotation Speed (rpm)

4-5

Tandem Row

Mesh Generation

The speed will be transferred to FINE™ graphical user interface and ease the input of boundary conditions later on. The sign of the rotational speed is positive (+) when the blade row is rotating in the positive θ direction, and negative otherwise 10. Select


The row type and row orientation settings are only information that will not impact or control the mesh generation process. 11.

Activate Tandem Row in order to set automatically the grid points distribution of the blade to blade mesh when setting the default topology

12. Activate


13. Close

the dialog box

14. Click-left

4-6

on Select All Rows

15. Select


16. Select


Tutorials

Mesh Generation

4-2.3

Tandem Row



on Select All Rows


19. Estimate



where: - ywall is the distance of the nearest grid point to the wall (in meter); - Vref is a reference velocity of the flow, for instance the inlet velocity (in m/s); - υ is the kinematic viscosity of the fluid (in m2/s), i.e. the dynamic viscosity divided by the density; - Lref is a reference length of the test case (in meter); - y+ is a non-dimensional value. Input the value of the Cell Width = <1e-2> [Millimeters] in Row Mesh Control.

Tutorials

4-7

Tandem Row

Mesh Generation

20. Select


The default skin-topology includes 5 blocks for each blade as follows: - the skin block is a O-mesh surrounding the blade - the inlet block is a H-mesh located upstream the leading edge - the outlet block is a H-mesh located downstream the trailing edge - the up block is a H-mesh located above the blade section - the down block is a H-mesh located under the blade section

Down Splitter 1 Inlet Splitter 1

Inlet Main Blade

Up Main Blade Up Splitter 1 Skin Splitter 1 Skin Main Blade

Down Main Blade

Outlet Splitter 1

Outlet Main Blade

4-2.4

Meridional Control

21. Go

to QAP Mesh Control

22. Keep



23. Control

4-8

24. Keep

data identical

25. Close

the dialog box

Tutorials

Mesh Generation

Tandem Row

4-2.5


26. Click-left

on main blade or splitter mesh in the blade-to-blade view

27. Go

to Mesh Control Topology

Row Mesh Control


By default, when tandem row is specified, matching connections (Matching Periodicity check button active) are applied at periodic boundaries and at connection between main blade and splitter.

Main Blade

Matching Connection

Splitter 1

28. Keep

Matching Periodicity activated and all other data identical for main blade and split-

ter In several turbomachinery types, the blades are highly staggered (Automatic High Staggered Blade Detection within AutoGrid™). If the solid angle at the inlet (outlet) of the machine becomes greater than 450 and if the location of the inlet (outlet) limits of the domain is close to the leading edge (trailing edge) of the blades, then the default topology is not suitable anymore since the cells located near the inlet (outlet) boundary become very skewed. To improve this unexpected behaviour, AutoGrid™ uses the High Staggered Blade Optimization. 29. Deactivate

Topology option

30. Go

to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view if necessary.

Tutorials

4-9

Tandem Row

Mesh Generation

By default, when tandem row is specified, the grid points distribution along the main blade and splitter will be adapted as presented on figure below. Splitter 1 N4

N5

N6

Main Blade N1

N2

N3 N4 = N1 + N2 N3 = N5 + N6

31. Click-left on

the number of nodes, make the proper modification in the entry box and press to confirm the modification The number of points specified is recommended to be 4xn + 1 (where n is an integer) to allow multigrid process on minimum 3 grid levels within FINE™. When tandem row is specified, to keep matching connections at periodic boundaries and at connection between main blade and splitter: + if the grid points distribution N1 and/or N2 is modified along main blade, N4 along splitter 1 has to be adapted accordingly; + if the grid points distribution N3 is modified along main blade, N5 and/or N6 along splitter 1 has to be adapted accordingly; + if the grid points distribution N4 is modified along splitter 1, N1 and/or N2 along main blade has to be adapted accordingly; + if the grid points distribution N5 and/or N6 is modified along splitter 1, N3 along main blade has to be adapted accordingly. Main Blade

Splitter 1

N2 ↑ N5 ↑

4-10

⇒ N4 ↑ ⇒ N3 ↑ Tutorials

Mesh Generation

Tandem Row

32. Visualize

the result in blade-to-blade view after selecting Generate B2B to regenerate the flow paths and the mesh in blade-to-blade plane


Grid Points option

the dialog box.


35. Go


on Select All Rows


38. Select



on the blade-to-blade window to activate that view (red border)

to the menu View-> Repetition

41. Increase

Nb Repet to <1> and Show

42. Close

the dialog box

43. Check


44. Select


45. Click-left


46. Click-left


47. Click-left on


48. Close

Tutorials

the dialog box

4-11

Tandem Row

Mesh Generation

Click Left





51. Close

the dialog box

4-2.6

3D Mesh Generation


4-12

on Select All Rows

on the icon Generate 3D and confirm (Start) the generation

Tutorials

Mesh Generation

Tandem Row


54. Close

4-2.7




on Select All Rows


57. Click-left


58. Click-right 59.

Tutorials



4-13

Tandem Row

Mesh Generation

4-2.8


60. Check


61. Select


4-14

Tutorials

Mesh Generation

Tandem Row


the dialog box

63. Check


64. Click


65. Close

the dialog box

66. Check


Detailed analysis of mesh quality on 3D mesh (in blocks, at boundaries and at FNMB) can be performed only once the 3D mesh has been generated. Information on orthogonality, angular deviation, aspect ratio, expansion ratio and cell width can be outlined in this window using the Type pull-down menu.

Click Left

Tutorials

4-15

Tandem Row

Mesh Generation

67. Select


68. Click-left


69. Click-left


70. Click-left on


71. Close

4-2.9 72.

the dialog box


4-16

Tutorials

TUTORIAL 5:

Cascade Configuration

5-1

Introduction

5-1.1

Introduction







Tutorials

5-1


Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of cascade configuration. It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • •

Read an existing geometrical file into AutoGrid™ v8; Define cascade configuration; Control the meridional and blade-to-blade mesh; Control the quality of the mesh in the blade-to-blade and 3D mesh.

5-1.2

Prerequisites


5-1.3

Problem Description

The problem to be considered is shown schematically here below. The project consists in the mesh generation of the T106 turbine blade cascade configuration.

5-1.4

Preparation



5-2

Tutorials

Introduction


For WINDOWS systems, you can access AutoGrid™ v8.x graphical user interface from the start menu going to /Programs/NUMECA software/fine8x/IGG or /Programs/NUMECA software/autogrid8x/IGG

4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the cascade configuration!


Tutorials

5-3


5-2

Mesh Generation

Mesh Generation


5-2.1 1.


2.


3.


4.

Activate Cascade option

5.

Choose the icon Start a New Project From Scratch

5-2.2


6.


7.


8.



Import and Link CAD


Click-left on File

10. Select 11.

Open...

cascade.dat file from the file chooser

Define the geometry orientation if necessary

• Select Geometry Axis... in the Edit menu • Adapt origin, stream and span direction if required - keep default • Apply

5-4

Tutorials

Mesh Generation



12. Define

the hub curve

• - click-left on all the curves defining the hub as they turn to yellow • Click-right and select Link to Hub Hub curve is displayed in the meridional view.

13. Define

the shroud curve

• - click-left on all the curves defining the shroud as they turn to yellow • Click-right and select Link to Shroud Shroud curve is displayed in the meridional view.

14. Define

the blade




Tutorials

5-5


Mesh Generation

• Click-left on the surface defining the blade when highlighted in blue (it turns to red or yellow)

Click Left

If the blade is defined by multiple surfaces, click-middle and -click-left allow to select all the surfaces defining the blade. The View/View Solid menu acts as a toggle and allows to visualize the surfaces that are active.


15. Define





• • • •

Click-left at blade leading edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Leading Edge Click-left at blade trailing edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Trailing Edge Leading and trailing edges are displayed in the meridional view.

5-6

Tutorials

Mesh Generation


When blade intersects hub and shroud, inlet and outlet are displayed in the meridional view. 16. Go

to File -> Exit The geometry of the cascade configuration can also be defined from a native ".geomTurbo" file. The ".geomTurbo" file format is structured in three main blocks: the header, the channel and the row(s) definitions. The header when defining a cascade configuration should contain the keywords "cascade yes".

The channel format contains the definition of the turbomachinery meridional contour (hub and shroud). It is composed by curves defined by a set of points. The ".geomTurbo" file must contain two channel curves named respectively "hub" and "shroud". The row definition contains the geometry of a complete row. The blade is defined by the pressure and the suction side surfaces identified by the keywords "pressure" and "suction". Both surfaces are specified by a set of cross sections of the blade at several spanwise location from hub to shroud. Each section is defined by a set of points from leading to trailing edge.

Tutorials

5-7


17. Click-left

Mesh Generation


18. Click-right 19. Enter

on row 1 and select Properties in the pop-up menu

the Periodicity (number of blades) to <79.9> The periodicity for cascade configuration corresponds to the pitch distance between two successive blades.

20. Enter

<0> in Rotation Speed (rpm) The speed will be transferred to FINE™ graphical user interface and ease the input of boundary conditions later on.

21. Select

Stator as a row type and Axial as a row orientation

The row type and row orientation settings are only information that will not impact or control the mesh generation process.

22. Close 23. Set

the dialog box

the scaling factor

• Go to Geometry Definition Units • Change the units to Millimeters

5-8

Tutorials

Mesh Generation


The "units" of the imported geometry must be changed to impose a scaling factor and a corresponding tolerance that will ensure correct treatment during the grid generation when computing for example the intersection. If not necessary, we recommend to keep the default settings (Scale Factor set to 1) 24. Click-left

on Select All Rows

25. Select


26. Select


5-2.3



on Select All Rows


29. Estimate



where: - ywall is the distance of the nearest grid point to the wall (in meter); - Vref is a reference velocity of the flow, for instance the inlet velocity (in m/s); - υ is the kinematic viscosity of the fluid (in m2/s), i.e. the dynamic viscosity divided by the density; - Lref is a reference length of the test case (in meter); - y+ is a non-dimensional value.

Tutorials

5-9


Mesh Generation

Input the value of the Cell Width = <5e-3> [Millimeters] in Row Mesh Control.

30. Select


The default skin-topology includes 5 blocks as follows: - the skin block is a O-mesh surrounding the blade - the inlet block is a H-mesh located upstream the leading edge - the outlet block is a H-mesh located downstream the trailing edge - the up block is a H-mesh located above the blade section - the down block is a H-mesh located under the blade section

5-2.4 31.

Meridional Control Go to QAP Mesh Control

32. Change


The number of flow path can be imposed as <2> in order to generate a 2D mesh. flow paths if necessary through Mesh Control -> Row Mesh Control -> Flow Paths Control

33. Control

• Set Cell width at Hub as <5.0> • Set Cell width at Shroud as <7.0> The hub and shroud are respectively considered as a euler wall and a mirror plane. For these reasons, the cell width at hub and shroud can be increased because there are no boundary layer to capture.

5-10

Tutorials

Mesh Generation


The Expert section allows the user to control the visualization, the shape and the parameters related to flow path smoothing. The meaning of these parameters is detailed in the user manual. The Manual Edition mode allows the user to control directly the block faces which are used to construct flow paths. Edges can be moved, segments can be created or modified and grid points distribution on segments can be controlled. More details can be found in the user manual. 34. Click

on Generate

35. Close

the dialog box

5-2.5


36. Click 37. Go

on Generate B2B

to Mesh Control Topology

Tutorials

Row Mesh Control


5-11


Mesh Generation



39. Deactivate

Topology option

40. Go

to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view if necessary

41. Click-left on

the number of nodes, make the proper modification in the entry box and press to confirm the modification



43. Deactivate

Grid Points option

44. Close

the dialog box

45. Move

default location of leading/trailing edge:

• Click-left in blade-to-blade view to activate the view (red border) • Zoom on leading edge • When leading edge highlighted in red (move the mouse on it), click-left and drag to move the leading edge location; click-right to access a popup menu allowing to impose the points distribution at leading edge (Properties)

5-12

Tutorials

Mesh Generation


Click Left

Click Right

Absolute Control Distance: the distance is given in absolute units and remain the same for each layer. Relative Control Distance: the distance is given in relative units (normalized with the blade width). First Cell Length: the distance is equal to the product of the cell width given by the user and the number of nodes. Another feature of this dialog box gives the control of the maximum expansion ratio of the cells in the streamwise direction along the wall. Switch on the button Desired Expansion Ratio implies that the number of grid points on the upper and lower side of the blade will be recomputed to ensure that the expansion ratio remain lower than the target value. The total number of points around the blade is then continuously updated.

• The above steps can also be applied on trailing edge • Visualize the result in blade-to-blade view after selecting Generate B2B to regenerate the flow paths and the mesh in blade-to-blade plane. to Mesh Control -> Active B2B Layer to specify the flow path (layer) on which the blade-to-blade mesh will be plotted in the blade-to-blade view

46. Go


on Select All Rows


49. Select

Generate B2B to regenerate the blade-to-blade mesh on new specified layer in the blade-to-blade view

Tutorials

5-13


Mesh Generation

Detailed analysis of mesh quality can be performed on Blade-to-Blade mesh after generation. Information on orthogonality, aspect ratio and expansion ratio can be outlined in this window using the Type pull-down menu and plotted in the blade-to-blade view on active layer selected in Mesh Control/ Active B2B Layer. 50. Check


51. Select


52. Click-left


53. Click-left


54. Click-left on


Click Left

55. Close

the dialog box



Optimization is performed in the form of smoothing and is executed on each layer using multi-block elliptic techniques. The number of Optimization Steps represents the number of iterations performed with the elliptic smoother. By default, 100 iterations are applied.

5-14

57. Keep


58. Close

the dialog box

Tutorials

Mesh Generation

5-2.6


3D Mesh Generation


on Select All Rows



5-2.7




on Select All Rows


64. Click-left


65. Click-right 66.

Tutorials



5-15


5-2.8

Mesh Generation


67. Check


68. Select


5-16

Tutorials

Mesh Generation



the dialog box

70. Check


71. Click


72. Close

the dialog box

73. Check



Click Left

Tutorials

5-17


74. Select

Mesh Generation


75. Click-left


76. Click-left


77. Click-left on


78. Close

5-2.9 79.

the dialog box


5-18

Tutorials

TUTORIAL 6:

Fin on Fan

6-1

Introduction

6-1.1

Introduction







Tutorials

6-1

Fin on Fan

Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of a fin on fan in bypass turbomachine applications. It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • •

Define geometry into AutoGrid™ v8; Control meridional flow paths especially at the fin and nozzle; Control the blade-to-blade mesh; Control the quality of the mesh in the blade-to-blade and 3D mesh.

6-1.2

Prerequisites

This tutorial does not require any particular prerequisite but it is strongly recommended for beginners to perform the basic tutorials 1 to 7 and the advanced tutorial 3.

6-1.3

Problem Description

The problem to be considered is shown schematically here below (meridional view). The project consists in the mesh generation of a bypass configuration with a fan including a fin.

Fin

6-1.4

Preparation



6-2

Tutorials

Introduction

Fin on Fan

For WINDOWS systems, you can access AutoGrid™ v8.x graphical user interface from the start menu going to /Programs/NUMECA software/fine8x/IGG or /Programs/NUMECA software/autogrid8x/IGG

4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the bypass configuration with a fin on fan!

Tutorials

6-3

Fin on Fan

Mesh Generation


6-2

Mesh Generation


6-2.1 1.


2.


3.


4.

Activate With ByPass and With Fin on Fan options The Fin on Fan option is only allowed for Bypass configuration.

5.

6-2.2

Choose the icon Start a New Project From Scratch


6.


7.


8.



Import and Link CAD

Graphic window opens, allowing geometry import.

6-4

Tutorials

Mesh Generation

9.

Fin on Fan

Click-left on File

10. Select 11.

• • • •

Open...

geometry.dat file from the file chooser

Define the geometry orientation if necessary Select Geometry Axis... in the Edit menu Adapt origin, stream direction if required - keep default Apply Close dialog box

12. Define

the hub curve

• Click-left on the curve defining the hub as it turns to yellow • Click-right and select Link to Hub Hub curve is displayed in the meridional view.

13. Define

the shroud curve

• Click-left on the curve defining the shroud as it turns to yellow • Click-right and select Link to Shroud Shroud curve is displayed in the meridional view.

Tutorials

6-5

Fin on Fan

Mesh Generation

14. Define

the nozzle curve

• Click-left on the curve defining the nozzle as it turns to yellow • Click-right and select Link to Nozzle Nozzle curve is displayed in the meridional view.

15. Define

the blade




• Click-left on first surface defining the blade when highlighted in blue (it turns to red or yellow)

• Click-middle to select the second surface defining the blade • - click-left on second surface defining the blade when highlighted in blue (it turns to red or yellow)

Click Left

Click Middle Click Left

The View/View Solid menu acts as a toggle and allows to visualize the surfaces that are active.

6-6

Tutorials

Mesh Generation

Fin on Fan


16. Define





• • • •

Click-left at blade leading edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Leading Edge Click-left at blade trailing edge line definition, inside the Import CAD window As it turns yellow, click-right and select Link to Trailing Edge Leading and trailing edges are displayed in the meridional view.

17. Define

fin on fan

The fin has to be defined by two curves defining respectively the upper and down sides of the axisymmetric fin.




• • • •

Tutorials

Click-left at upper side curve of the fin, inside the Import CAD window As it turns yellow, click-right and select Link to Fin Up Click-left at lower side curve of the fin, inside the Import CAD window As it turns yellow, click-right and select Link to Fin Down

6-7

Fin on Fan

Mesh Generation

When blade intersect hub and shroud, inlet and outlet are displayed in the meridional view. Control lines are automatically appearing for the control of the flow paths around the fin and the bypass nozzle.

18. Go

to File -> Exit The geometry of the fin can also be defined from a native ".geomTurbo" file. The ".geomTurbo" file format is structured in three main blocks: the header, the channel and the row(s) definitions. The header when defining a bypass configuration should contain the keywords "byPass yes".

The channel format contains the definition of the turbomachinery meridional contour (hub and shroud). It is composed by curves defined by a set of points. The ".geomTurbo" file must contain two channel curves named respectively "hub" and "shroud". The row definition contains the geometry of the fin and the complete row. The fin is defined by two curves: upper_curve and lower_curve defining the axisymmetric surfaces that will be used to define the fin. The blade is defined by the pressure and the suction side surfaces identified by the keywords "pres-

6-8

Tutorials

Mesh Generation

Fin on Fan

sure" and "suction". Both surfaces are specified by a set of cross sections of the blade at several spanwise location from hub to shroud. Each section is defined by a set of points from leading to trailing edge.

19. Click-left


20. Click-right

Tutorials

on row 1 and select Properties in the pop-up menu

21. Enter

the Periodicity (number of blades) to <40>

22. Keep

<500> in Rotation Speed (rpm)

6-9

Fin on Fan

Mesh Generation

The speed will be transferred to FINE™ graphical user interface and ease the input of boundary conditions later on. The sign of the rotational speed is positive (+) when the blade row is rotating in the positive θ direction, and negative otherwise 23. Select


The row type and row orientation settings are only information that will not impact or control the mesh generation process. 24. Activate


25. Close

the dialog box

26. Click-left


27. Click-right


28. Set

Width At Leading Edge = <0.012> [Meters]

29. Set

Width At Trailing Edge = <0.012> [Meters]

The width at leading/trailing edge allows to specify the size of the gap respectively at the leading and trailing edge of the blade. The gap curve is then constructed as a linear offset of the hub (or the shroud) according to these values. 30. Click-left

6-10

on Select All Rows

31. Select


32. Select


Tutorials

Mesh Generation

6-2.3

Fin on Fan



on Select All Rows


35. Estimate



where: - ywall is the distance of the nearest grid point to the wall (in meter); - Vref is a reference velocity of the flow, for instance the inlet velocity (in m/s); - υ is the kinematic viscosity of the fluid (in m2/s), i.e. the dynamic viscosity divided by the density; - Lref is a reference length of the test case (in meter); - y+ is a non-dimensional value. Input the value of the Cell Width = <1e-5> [Meters] in Row Mesh Control.

Tutorials

6-11

Fin on Fan

Mesh Generation

36. Select


37. Click-left

on yes to perform an automatic switch to matching topology that is required because of the control lines used to define the fin that are on the blade (row 1)

6-2.4

Meridional Control When overlapping detected in the flow paths, a warning is appearing at the bottom of the graphical user interface. In addition, the expansion ratio is plotted in the message box.

38. Control

bypass - nozzle - fin points distributions

• Click-left on Select All Rows • Click-left on Mesh Control -> Row Mesh Control -> Flow Paths Control -> Expert • Deactivate View Flow Path to plot the grid used to generate the flow paths • Close dialog box

6-12

Tutorials

Mesh Generation

Fin on Fan

• Click-left on • Click-left on number of flow paths down the nozzle, decrease to <41> to add more flow paths between the nozzle and the fin


Click Left

More information about the control of the nozzle and bypass points distribution are provided in advanced tutorial 3.

• • • •

Click-left on control line defining the nozzle topology when highlighted in yellow Click-left on control point defining the control line Move control point at desired location Click-left on control point to validate its new location

Click Left Click Left

The exact coordinates of the control points can also be introduced with clickright on the control point; a dialog box appears, enabling the user to enter the point coordinates in (rz) mode.

Tutorials

6-13

Fin on Fan

Mesh Generation


39. Check

quality of the flow paths

• Click-left in meridional view to activate it (red border) • Click-left on • Select quality criteria using the Type pull-down menu • Click-left on Show chart to visualize the distribution of selected criteria in the form of an histogram. The histogram is drawn for each row

• Click-left on part of the histogram to plot the concerned cells in the meridional view • Click-left on More info button to obtain information about minimum and maximum values of the selected criteria


Click Left

6-2.5


40. Click 41. Go

on Generate B2B

to Mesh Control

6-14

Row Mesh Control


Topology

Tutorials

Mesh Generation

Fin on Fan

By default, matching connections are applied at periodic boundaries because of the control lines used to control the flow paths along the fin that are on the blade (row 1). You can see the periodic boundary by showing the repetitions. 42. Click-left 43. Go

on the blade-to-blade window to activate that view (red border)

to the menu View-> Repetition

44. Increase

Nb Repet to <1> and Show

45. Close

the dialog box

46. Keep

Matching Periodicity activated and all other data identical In several turbomachinery types, the blades are highly staggered (Automatic High Staggered Blade Detection within AutoGrid™). If the solid angle at the inlet (outlet) of the machine becomes greater than 450 and if the location of the inlet (outlet) limits of the domain is close to the leading edge (trailing edge) of the blades, then the default topology is not suitable anymore since the cells located near the inlet (outlet) boundary become very skewed. To improve this unexpected behaviour, AutoGrid™ uses the High Staggered Blade Optimization.

47. Deactivate

Topology option

48. Go

to Mesh Control Row Mesh Control B2B Mesh Topology Control -> Grid Points to control the number of grid points in the blade-to-blade view if necessary Click-left on the number of nodes, make the proper modification in the entry box and press to confirm the modification. The number of points

Tutorials

6-15

Fin on Fan

Mesh Generation

specified is recommended to be 4xn + 1 (where n is an integer) to allow multigrid process on minimum 3 grid levels within FINE™. Visualize the result in blade-to-blade view after selecting Generate B2B to regenerate the flow paths and the mesh in blade-to-blade plane. 49. Keep

default points distribution


Grid Points option

the dialog box


52. Go


on Select All Rows


55. Select


56. Check


57. Select


58. Click-left


59. Click-left


60. Click-left on


Click Left

6-16

Tutorials

Mesh Generation

Fin on Fan

61. Close

the dialog box





64. Close

the dialog box

6-2.6

3D Mesh Generation


67. If

on Select All Rows


at the end of the generation, a warning as presented below appears, click-left on Ok

This warning prevents the user that when checking the grid quality (angular deviation along J) if a discontinuity is detected, the user has to reduce the expansion ratio in the Mesh area of the B2B Mesh Topology Control dialog box. In addition, the blade-to-blade mesh can be plotted on the concerned active layer (i.e. layer 132) by repeating the steps 52 to 55.

Tutorials

6-17

Fin on Fan

Mesh Generation


68. Close

6-2.7




on Select All Rows


71. Click-left


72. Click-right 73.

6-18



Tutorials

Mesh Generation

6-2.8

Fin on Fan


74. Check


75. Select



the dialog box

77. Check


78. Click

on Apply The computation of the negative volumes is performed first. Negative cells can be outlined in the mesh pushing View neg cells button. Beware that the visualization of negative cells can be memory consuming when a large number of cells must be displayed. It is then advised to first check the number of negative cells by pressing the Apply button.

Tutorials

6-19

Fin on Fan

Mesh Generation

It is mandatory to remove all negative cells before the calculation can be started.

79. Close

the dialog box

80. Check




82. Click-left


83. Click-left


Click Left

84. Click-left on


6-20

Tutorials

Mesh Generation

Fin on Fan

85. Close

6-2.9 86.

the dialog box


Tutorials

6-21

Fin on Fan

6-22

Mesh Generation

Tutorials

TUTORIAL 7:

3D Technological Effect Casing Treatment

7-1

Introduction

7-1.1

Introduction







Tutorials

7-1


Introduction

others can complete the machine. Due to the complexity of the blade shapes, the presence of technological elements and the rotation of machine, the nature of the flow is strongly three-dimensional, often depicting complex flow paths. This tutorial is particularly adapted to the mesh generation of casing treatments (3D technological effects) for turbomachines. It makes exclusive use of AutoGrid™ v8 and describes the main actions required to mesh the configuration of interest. In this tutorial you will learn how to:

• • • •

7-1.2

Read an existing project file into AutoGrid™ v8; Adapt the existing project file; Generate and control the mesh in the technological effect (casing); Control the quality of the mesh in the 3D mesh.

Prerequisites

This tutorial does require to perform the mesh generation of the NASA rotor 37 explained in basic tutorial 1. Furthermore, it is strongly recommended for beginners to perform the basic tutorials 2 to 7 too.

7-1.3

Problem Description

The problem to be considered is shown schematically here below. The project consists in the mesh generation of a casing treatment (3D technological effect) for the NASA rotor 37. 0.0356 0.02

Rotor-Stator

AutoGrid Mesh

7-1.4

3d techno effect

Preparation



7-2

Tutorials

Introduction



4

• Access the menu Modules, select AutoGrid and confirm "yes" to enter AutoGrid™ v8. You’re now ready to start the grid generation process and mesh the configuration presenting a casing treatment (3D technological effect)!

Tutorials

7-3


Mesh Generation


7-2

Mesh Generation


7-2.1

Open Existing Mesh Project

1.

Click on Select a Project File in the Open Turbo Project Wizard dialog box

2.

Select the file NASA-Rotor-37.trb

3.

Click Open to load the selected project

The Open Turbo Project Wizard dialog box enables the user to retrieve a ".trb" file (with associated grid) including the data required to regenerate a mesh on an identical or similar geometry. In this tutorial, these data will be progressively introduced based on the geometry of the project case.

7-2.2

Adapt Mesh Project

4.


5.


6.



Import and Link CAD

Graphic window opens, allowing geometry import.

7-4

Tutorials

Mesh Generation


7.

Click-left on File

Open...

8.


9.

Define the new shroud curve

• Click-left on the curve (new_shroud) as it turns to yellow • Click-right and select Link to Shroud New shroud curve is displayed in the meridional view.

New Shroud

10. Go 11.

to File -> Exit

Click-left on the " + " before row1 in QAP to get the blade information

12. Click-left on

Blades the contextual menu

Main Blade

Shroud gap, click-right and select Properties in

13. Set

Width At Leading/Trailing Edge to <0.0156> to define the main blade tip in addition of the 3D technological effect thickness (0.0356 - 0.02)

Tutorials

14. Keep

all other data identical

15. Close

the dialog box

7-5


16. Control

Mesh Generation

flow paths through Mesh Control -> Row Mesh Control -> Flow Paths Con-

trol 17. Set

Cell width at Shroud to <0.001>

18. Keep

all other data identical

19. Click

on Generate to regenerate flow paths

20. Close

the dialog box

21. Click

on Generate B2B (active layer = 0%)

to generate blade-to-blade mesh by default on hub



7-6

on the icon Generate 3D and confirm (Start) the generation

Tutorials

Mesh Generation


Once 3D grid generation is completed, grid quality is performed and displayed. Minimum cells skewness, maximum expansion ratio and aspect ratio are reported, among others. Data are available for the entire mesh separately for every entity (row, technological effect, bulb). Data related to grid quality report are automatically stored in a report file, once the project file is saved.

24. Close

7-2.3

the dialog box

3D Technological Effect Generation

7-2.3.1 Configuration Control on Rows Definition -> row 1 in the Quick Access Pad (QAP) to active the current row, if not done already


Tutorials

on the button Add 3D Effect to add a 3D technological effect in the configuration

7-7


Mesh Generation

7-2.3.2 Geometry Definition on Rows Definition -> row 1 -> 3d techno effect 1 in the Quick Access Pad (QAP) if not active already



Import and Link CAD

Graphic window opens, allowing geometry import. 29. Select

the curves and surfaces defining the active 3D technological effect

• -click-left on all the curve(s) (from curve_1 to curve_8) as they turn to yellow • -click-left on all the surface(s) (from surface_1 to surface_3) as they turn to blue • Click-right and select Link to 3D Effect

30. Go

to File -> Exit

on Rows Definition -> row 1 -> 3d techno effect 1 in the Quick Access Pad (QAP) if not active already

31. Click-left

32. Click-right

on 3d techno effect 1 to get the contextual menu and select Edit to access the 3D technological effect edition mode

Curves and surfaces defining the selected 3d technological effect are displayed in the 3D view.

7-8

Tutorials

Mesh Generation


Curves and surfaces defining the 3d technological effects are specified in the ".geomTurbo" file (see User Manual for more details). In the edition mode, it is not recommended to define new geometrical entities by using the Geometry menu. Otherwise, when relaunching the template including the 3d technological effect, problems may occur (see User Manual for more details).

7-2.3.3 Topology & Mesh Control The domain defining a technological effect must be filled by several structured 3D blocks (like in IGG™). The block edges are mapped on the geometry. The Grid subpad provides the tools to create and control the blocks 33. Click-left

on Insert New Face icon in the Grid subpad to start to fill the geometry

34. Click-left

to locate the first corner of the 2D block (yellow spot when attracted on existing

curve) 35. Click-left

to locate the opposite corner of the 2D block

36. Click-left

to create the 2D block

37. Click-left

on vertex (when highlighted in yellow) of the 2D block to move it when neces-

sary 38. Click-left 39. Repeat

Tutorials

to fix the new position of the vertex on the geometry

steps 37 and 38 for all vertices defining the 2D block

7-9


Mesh Generation

40. Repeat

steps 33 to 39 in order to fill the "inlet" geometry of the technological effect with two new faces as presented in the figure below

41. Change

• • • •

the number of points on edges:

Click-left on edge (highlighted in yellow) Click-right and select Segment/Set Number of Points Set number of points (by default set to 9) as presented in figure below Apply

13

25

25 9

9 13

The number of points specified is recommended to be 4xn + 1 (where n is an integer) to allow multigrid process on minimum 3 grid levels within FINE™. 42. Change

the points distribution on edges defining two groups:

• Click-left on one edge (highlighted in yellow)

7-10

Tutorials

Mesh Generation


• Click-right and select Segment/Distribution: a new window appears

• • • • •

Click-left on Define/Edit Group Click-left on Create Set a userdefined group name - to validate Click-left to select edges to include in group-1 Click-middle to add the selected edge in the group-1 as presented in figure below

If the menu to select and/or add edges in a group is no more available, clickleft on the group in the list and click-left on Modify.

• Click-left on Create • Set a userdefined group name - to validate • Click-left to select edges to include in group-2

Tutorials

7-11


Mesh Generation

• Click-middle to add the selected edge in the group-2 as presented in figure below

• • • •

Close the dialog box Select group-1 under Group name Impose Hyperbolic Tangent with a cell width of <0.0003> at start and end Click-left on Apply to group

• Select group-2 under Group name • Impose Hyperbolic Tangent with a cell width of <0.0003> at start and <0.001> at end • Click-left on Apply to group

43. Close

7-12

the dialog box

Tutorials

Mesh Generation


44. Create

the 3D blocks starting from the 2D grid faces:

• Click-left on edge to select grid face (highlighted in white or black) • Select Block by Face Translation • In keyboard input area, type to allow edge creations - <1> to select translation - <0 0 25.3466> as translation vector - to avoid geometry creation - to avoid to intersect selected surfaces: a 3D block is created by translating the 2D grid face

• Repeat the above steps for the others two 2D grid faces

45. Connect

the 3D blocks together:

• Select Connect / Face-Face • Click-left on edge to select the reference face (highlighted in white or black) of the concerned block (highlighted in red)

• • • •

Tutorials

Click-middle to aknowledge Click-left on edge to select the second face to connect Click-middle to aknowledge: a new window appears Click-left on All: faces appear in green or red if well connected

7-13


Mesh Generation

• Repeat the above steps for the others two faces to connect

• Close the dialog box connect_faces 46. Change

• • • •

the number of points in the axial direction:

Click-left on edge (highlighted in yellow) Click-right and select Segment/Set Number of Points Set number of points (by default set to 9) as presented in figure below Apply

47. Map

the 3D blocks on the imported curves:

• Click-left on vertex (when highlighted in yellow) of the 3D block to move it on curves • Click-left to fix the new position of the vertex on the geometry • Repeat above steps for all vertices defining the 3D blocks

Click-Left

Click-Left

7-14

Tutorials

Mesh Generation


48. Generate

3D mesh by click-left on Block 6 Bnd and select blocks 8 to 10 - Apply

7-2.3.4 Boundary Conditions & Quality Control 49. Define

• • • • •

the periodicity of the blocks in the 3d technological effect:

Select Periodicity in the Grid menu Enter <8> in Block area Select ROTATION Adapt Axis and Number Of Periodicity as presented below - to validate Apply

720

• Repeat above steps for block 9 and 10 • Close the dialog box 50. Adapt

and check boundary conditions:

• Select Boundary Conditions in the Grid menu • Click on Search to define automatically the connections between blocks 8, 9 and 10: 2 connections and 1 periodic connection are created

Tutorials

7-15


Mesh Generation

• Type under Name area • -left-click on the patches as presented in figure below • Click-left on button Set Patch Type and drag to ROT to change shroud type from solid (SOL) to rotor/stator (ROT)

Click-Left Click-Left

• Select UND under Type area • -left-click on the patches as presented in figure below • Click-left on button Set Patch Type and drag to ROT to change type from undefined (UND) to rotor/stator (ROT)

Click-Left

• -left-click on the patches as presented in figure below • Click-left on button Set Patch Type and drag to SOL to change type from undefined (UND) to solid (SOL)

Click-Left

7-16

Tutorials

Mesh Generation


• Select UND under Type pull-down menu and check that no patches are in the patch list still set with an undefined type It is important to make sure that no undefined patches (UND) are present in the mesh. In that case, these can usually be removed by increasing the tolerance and launching the Search procedure.

• Close the dialog box 51. Check


- Apply

The computation of the negative volumes is performed first. Negative cells can be outlined in the mesh pushing View neg cells button. Beware that the visualization of negative cells can be memory consuming when a large number of cells must be displayed. It is then advised to first check the number of negative cells by pressing the Apply button. It is mandatory to remove all negative cells before the calculation can be started. 52. Check



• Select quality criteria using the Type pull-down menu • Click-left on Show chart to visualize the distribution of selected criteria in the form of an histogram. The histogram is drawn per block (0 = all blocks)

• Click-left on part of the histogram to plot the concerned cells in the 3D view • Click-left on More info button to obtain information about minimum and maximum values of the selected criteria

• Close the dialog box 53. Click

on Close Edition Mode All the actions performed during an editing session are stored in the template file (".trb") and can be replayed on similar geometries.

7-2.4 54.

Tutorials

Save Project Go to File -> Save Project As to save mesh and template files

7-17


Mesh Generation

The mesh files (7 files) contain the multiblock mesh topology, geometry and grid points and the boundary condition types: ".bcs", ".cgns", ".geom" (".xmt_txt"), ".igg", ".config" and ".qualityReport".The meaning of these files is detailed in the user manual. The template files (4 files) contain the parameters and the geometry needed to reproduced the mesh with AutoGrid™: ".geomTurbo" (".geomTurbo.xmt_txt"), ".trb" and ".info". The meaning of these files is detailed in the user manual.

7-18

Tutorials

Tutorial Guide AutoGrid 82 1 Advanced-Acrov5

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