TRAINING REPORT
NAVAL SCIENCE & TECHNOLOGICAL TECHNOLOGICAL LABORATO ABORATOR RY (NSTL) (NSTL),, VISHAKAPATNAM
Submitted By: Himanshu Sharma VII Semester Roll No. 14 D.O.S.T
INTRODUCTION TO NSTL
In order to meet the requirements of Naval R&D in the field of Underwater Weapons, Warship Technology and ydrodynamic Research, a decision was ta!en to set up a ma"or Naval #ystem #ystemss $a%ora $a%orator tory y at isa! isa!hapa hapatna tnam' m' The Naval Naval #cienc #ciencee and Techn Technolo ologic gical al $a%ora $a%oratory tory (N#T (N#T$) $) was was thus thus set set up on *+th *+th ugus ugustt -./. -./. in the the prem premis ises es of ndhr ndhraa Univ Univer ersi sity ty,, isa!hapatnam' In these three and half decades this la%oratory has grown in strength and performance %y ma!ing many unique contri%utions in the fields of Underwater We Weapons, apons, Warship Technology 0oncepts, and 12perimental ydrodynamic Research' #pread over an area of -.3 acres on the west of National ighway 4 near isa!hapa isa!hapatnam tnam airport, airport, it has many wor! centers and facilities for high5end research activities' 6eeping pace with rapid growth of technology, the la%oratory has also grown manifold in term termss of pro" pro"ec ects ts,, scie scienti ntifi ficc and tech technol nolog ogic ical al infr infras astr truc uctu ture re devel developm opment ent,, tech technic nical al pu%lications and talented human resources' 7any products and systems have %een delivered to Indian Navy and in the process N#T$ has received many national awards for its technological e2cellence and innovations'
VISION AND MISSION
N#T$ has esta%lished the competence to wor! towards design and development of underwater weapons and associated systems and structural design of naval platforms' The vision and current mission of the la%oratory are as follows8
VISION
To %e a Self Reliant Centre of Excellence in •
Torpedoes, underwater targets and decoys, ship fire control systems and underwater mines with competitive and cutting edge technologies
•
ydrodynamics with e2pertise for supporting indigenous design of marine vehicles and provide comprehensive model test facilities
•
#tealth technology for Naval platforms
MISSION •
Design, development and evaluation leading to production of torpedoes, mines, targets, decoys, fire control systems and induction into services and also to esta%lish test facilities for the same
•
1sta%lish world class ydrodynamic test facilities for evolving design criteria through model tests for surface and su%5surface vehicles and torpedoes
•
Develop structural design capa%ilities and materials for mitigation of radar, infrared, magnetic, acoustic and 1$91 signatures leading to stealthier platform
MODEL ANALYSIS
7odels have %een used from the %eginning of recorded history for visuali:ing the structure as well as for planning the sequence of construction' In general ship models en"oyed a long and useful history dating %ac! to early 1gyptian' Wor!ing model %ecame a common usage during the industrial revolution' 7odeling of fluid mechanics phenomena started with e2pe riments of Reynold and 9roude wherein they developed the criteria for viscous and inertial effects' #tructural models have %een used for a long time and played a ma"or role in structural engineering and research' In ocean engineering models are playing a ma"or role where the data from the model are used for design or operation of the prototype In all fields of engineering model testing has %een adopted for various reasons' #ome are, -' When a pro%lem cannot %e solved %y analytical method' *' To o%tain empirical coefficients required for the equations predicted' ;' To su%stantiate the results of a new analytical tool' 3' To investigate failures' 4' To demonstrate visually and with credi%ility what could happen in e2treme conditions'
The Modeling Proce
successful model study is one that is characteri:ed %y careful planning of man y diverse steps and stages that goes into modeling process' n e2perimental study itself is an engineering pro"ect and "ust as in any pro"ect logical and careful sequencing is a%solutely essential' The following sequence can %e employed' -' Define the scope of the pro%lem' Decide what is e2pected from the model and what is not' *' Decide the required level of relia%ility or accuracy'
;' #pecify similitude requirement for geometry, material, loading and e2trapolation of results'
' Test facilities in the case of hydrodynamic testing and loading equipment for structural model tests are %oth important aspects which influence the selection of scale factor and model tests as a whole' ?' Instrumentation is an area where adequate attention should %e given' @ased on the relia%ility requirement and the scope of the programme, instrumentation should %e planned' In some cases instrumentation has to %e installed during the fa%rication of the model' .' A%serving model during the tests can reveal many interesting facts which may escape the attention otherwise'
Technical facilitie In order to carry out in5house research and support the indigenous efforts in ship%uilding and underwater weapon and platform development programmes of the Navy, N#T$ has set up the following test facilities
-) igh #peed Towing Tan! (#TT) *) 0avitation Tunnel (0T) ;) Wind Tunnel (WT) 3) ertical
mplitude
ori:ontal
7otion
7echanism
($<77)
!" #igh S$eed To%ing Tan& '#STT"
It is a hydrodynamic test facility recogni:ed %y International Towing Tan! 0onference (ITT0)' The tan! is fitted with a high speed towing carriage which runs at a ma2imum speed of *+ mBsec and runs on parallel rails which are fitted to have a tolerance of +'* mmover-++ m length and it follow the earthCs curvature' It is fitted with a wave generator at one end to simulate random and irregular sea conditions while testing the models' It is also equipped with a model ma!ing wor!shop to ma!e the scale down models of ships and su%marines to carry out the model tests for determining the performance characteristics and evaluation of the power plant requirements, etc' The other features of igh #peed Towing Tan! (#TT) are given %elow8
a) Tan! Dimension, m
4++ 2 ? 2 ?
%) 0arriage #peed, mBs head *+ (ma2) stern ; (ma2) With accuracy of +'- of set speed c) Wave =enerator
Dual flap type capa%le of generating regular and irregular waves (unidirectional) up to wave height of +'4 m'
d) #peed 0ontrol @y Ward $eonard #ystem feeding power through current conductors to ? in num%er -*. !W D0 drive motors'
The facility is equipped with a $arge mplitude ori:ontal
Tests m long heavy weight torpedo with
Teting of foil cata(aran in high $eed to%ing tan&
)" Ca*itation T+nnel
The 0avitation Tunnel at N#T$ is one of the most modern and the state5of5art facilities in the world' This is used for study of cavitation inception of %ody profile and propellers' It is also used for the study of coustic measurements due to cavitation of propellers' This facility can provide a water flow speed of -4 mBsec and create cavitation num%ers +'+; to -+' In order to design highly efficient propellers for applications to naval ships and platforms it is essential to carry out tests on these propeller models in the cavitation tunnel' The features of cavitation tunnel are given %elow8
a) Test #ection si:e
-'+ 2 -'+ 2 /'+ m long with an acoustic through positioned %elow the test section housing ? in no' @&6 hydro5phone array (
%) Drive #ystem
Thyristor controlled >++ !W D0 electric motor driving *'- m diameter fi2ed pitch > %laded a2ial flow impeller with . stator %lades'
c) 7a2imum Test
elocity in
-4mBs
#ection
d)
f) @ac! ground noise
-+5;++ !
The tunnel is equipped with an utomatic 0ontrol #ystem (0#) for its operation and controlH Data cquisition & nalysis #ystem (D#) for conduct of tests, acquisition of test data, analysis and prediction of results' It is also provided with a stand alone coustic
7easurement #ystem (7#) for acoustic measurements, analysis and e2trapolation to full scale results' arious types of towing and propulsion dynamometers, component %alances, wa!e ra!e, hydro5phones pressure transducers, photographic and video recording systems and stro%oscopes are also availa%le to conduct model tests' Tet Perfor(ed in CT
-' ' Wa!e survey' ?' 7easurement of hull pressure fluctuations induced %y propeller and cavitation' .' 7easurement of acoustic radiation caused %y cavitating and non5cavitating propeller and hull'
Tet Section of ca*itation T+nnel
Ti$ Vortex Ca*itation
Ca*itation of Tor$edo Noe Cone
Teting of contrarotating $ro$eller
," -ind T+nnel
wind tunnel to study the aerodynamic characteristics of surface and su%merged platforms and underwater weapons has %een set up at N#T$ with a test section of -'4 2 -'4 2 3 m' ma2imum
speed of /+ mBsec can %e produced with a -*4 !Wfan in this wind tunnel' The detailed features are given %elow8 a) Test #ection si:e
-'4 2 -'4 2 3'+ m long 3'; 2 3'; 2 3'+ m long
%)
c) 0ontraction No::le
arying from 3';m 2 3'; m square to -'4 2 -'4 m squareH 3'+ m long arying from -'4 2 -'4 m square to ;'4 m diameterH >'? m
d) Diffuser
long
e) 9an #i:e
;'+3 m diameter made of 09R<
f) Drive 7otor
-*4 !W D0 motor at >4+ rpm
g) 7a2imum #peed at Test #ection
/+ mBs
The Wind Tunnel is equipped with pro"ection manometers, differential pressure transducers, velocity measuring pro%es, vertical catheto5meters, hot film anemometers, 3? port #canivalve traversing gear as well as <0 %ased data acquisition system and analysis software pac!ages'
Tet Perfor(ed in -ind T+nnel
-' 9low visuali:ation and %oundary layer studies for underwater vehicles' *' Wa!e survey and velocity distri%ution %ehind a %ody for propulsor development ;'
3' 1stimation of forces and moments on control surfaces of a su%merged %ody, etc'
-ind t+nnel at NSTL
-a&e (ea+re(ent
Pro$+lion tet for $+($ .et
Aerofoil ection in %ind t+nnel
Planar Motion Mechani( S/te( 0" Vertical Planar Motion Mechani(
The <77 is used for determining the hydrodynamic coefficients required for prediction of sta%ility and control characteristics of su%merged %odies %y testing the model in ve rtical plane' 9ollowing are the main components of the <77 system
-' 7odel #upport and
•
Roll8 F5 * deg
•
9ive discrete frequency for dynamic motion8 +'* 5 +'> :
iii'
4' Dynamometry includes modular force gauges, roll gauge, rudder torque gauge, model propulsion system, etc' /' 0ontrol 1quipment and Data cquisition #ystem, located on %oard carriage are used for setting the test parameters, remote control of model and data logging
Teting of +1(erged 1od/ (odel +ing VPMM 2" Large A($lit+de Planar Motion Mechani(
The equipment is used for study of maneuvering and control effectiveness of surface ship models %y determining the complete set of hydrodynamic coefficients essential for formulation of mathematical models of ship motion and to carry out computer simulation of tra"ectories of the vessels for a wide variety of maneuvers of practical interest' The equipment comprises of the following -' Integrated Towing #ystem, capa%le of towing 35> m long models up to ;+++ !g displacement and up to a speed of ;'4 mBsec for > m long and > mBsec for 3 m long models *' eel & Roll 7echanism, allows model to %e free in heel and roll during test and impart rolling motion as required ;' 7odel Trac!ing #ystem, consisting of 4 video cameras for on5line recording and display of / motions and course of the model in calm waters and in waves 3' Drift ngle pparatus, to set drift angle upto8t ;+ deg at * deg intervals e) #way pparatus, capa%le of producing sway amplitude from + to -+++ mm 4' 9requency #etting pparatus, for imparting oscillatory motion of +'+- 5 +'; : to the model /' Jaw pparatus
>' Rudder ngle pparatus, for setting rudder angle of8t 34 degrees at increment of * degrees ?' 0ontrol #ystem, all apparatus are controlled %y servo motors through power amplifiers containing overload and control switches .' Dynamometry, includes force gauges, model propulsion system and rudder gauges and actuators
-+' <0 %ased Data cquisition & nalysis #ystem, includes *+ channel conditioning units for
acquiring and processing signals from sensors, all acquisition and on 5 line B off5
line analysis programs
Tet Perfor(ed %ith PMM S/te(
-' Resistance and self propulsion tests *' #tatic tests, in vertical plane for su%merged %odies using <77 and in hori:ontal plane for surface ships using $<77, for estimating forces and moments at different angles of attac! drift ;' Dynamic tests, in vertical plane using <77 for su%merged models, such as pure pitching, pure rolling, and pure heaving and in hori:ontal plane using $<77 3' 7aneuvering tests for high speed crafts su%"ected to large roll B heel during turning'
Teting of S+rface hi$ (odel +ing LA#PMM
TYPES O3 TESTS
Reitance tet
Resistance e2periments are carried out with ship models to determine the resistance of the model and there%y of the ship in a given condition' #uch e2periments are useful in optimi:ing the hull form and for predicting the po wer requirements of ship at a specific speed'
O$en -ater Ex$eri(ent
The open water e2periment is to determine the open water characteristics of a propeller' geometrically similar model is made of the propeller, the si:e of the model %eing governed %y the si:e of the ship model if it is intended to %e used to use the model for ship self5propulsion tests also' If only open water tests are to %e carried out, when generating propeller methodical series for e2ample, the model propeller is made somewhat larger, its si:e depending on the capacity of propeller dynamometer availa%le' ma"or concern is that flow should %e sufficiently tur%ulent' It can %e facilitated %y8 KL ma!ing the propeller sufficiently large KL%y giving a highly polished propeller surface When sufficient tur%ulence (;'*2-+4 at +'>R) is not attained tur%ulence needs to %e artificially stimulated %y roughening the leading edges of the %lades'
The propeller dynamometer measures the thrust and torque of the propeller' The propeller shaft e2tends a sufficient length from the %oat to ensure that the flow around the propeller is not distur%ed %y the %oat' fairing cap is provided at the forward end of the propeller %oss' The open water %oat is %allasted so that the propeller shaft is hori:ontal and its depth %elow the water surface at least equal to the model propeller diameter'
The open water e2periment is conducted %y towing the open water %oat at a steady speed while running the propeller at a constant revolution rate' The speed of the %oat (i'e' speed of advance
), and the revolution rate n, thrust T and torque M of the propeller are measured in each run' The speed of advance is varied in steps from :ero to the value at which the propeller thrust "ust %ecomes negative' The measured thrust and torque are corrected for the idleO thrust and torque measured %y a dynamometer when the e2periment is carried out with a dummy %oss of equal weight replacing the propeller'
The open water characteristics of model propeller can %e easily calculated from the measured values of and n, and corrected values of T and M' The open water characteristics of the ship propeller will %e slightly different %ecause of the difference in ReynoldCs num%ers of the model propeller and ship propeller'
Self Pro$+lion Tet
#elf propulsion e2periments are used to determine the p erformance of the ship hull and propeller ta!en together' #elf propulsion e2periments gives8
o
Delivered power at a given speed of the ship
o
The revolution rate of the ship propeller at a given speed of the ship
o
Wa!e fraction
o
Thrust deduction fraction
o
Relative rotative efficiency
9or a self propulsion test model propeller is fitted in its correct position at the stern of the ship and connected to a propeller dynamometer for measuring the thrust and torque o f the propeller at various revolution rates' The ship model should %e fitted with all the appendages as possi%le, particularly those lying in the propeller slipstream, e'g' a rudder' The ship model is fitted to a resistance dynamometer, which in this test measures the force required to ma!e the ship model move at a constant speed with the propeller running' The ship model is accurately %allasted so
that it floats at the correct waterline' The model is then towed at steady speed with the propeller running at constant revolution rate, and the thrust and torque of the propeller and the force applied to the ship model through the resistance dynamometer are applied'
#YDRO3OIL
ydrofoil craft uses hydrodynamic lift generated %y the wings' #urface piercing foils has good sta%ility and su%merged hydrofoil with ride control system has good sea !eeping qualities can %e employed as fast attac! craft and transport vessel' #alient features8 •
igh #peed P power ratio
•
Wide operating range
•
=ood maneuvering
•
igh endurance, low speed
•
$oss in waves, good sea worthiness
SUR3ACE E33ECT CATAMARAN
This is an advanced hy%rid marine vehicle which reduces drag using aerostatic lift, aerodynamic lift and hydrodynamic lift can %e used for river and shallow water transportation #alient features8
•
igh #peed P power ratio
•
Wide operating range
•
$arge dec! area
•
igh sta%ility
•
$arge carrying capacity
•
=ood stealth features
3OIL CATAMARAN
9oil craft is a high hy%rid hull from com%ining features of catamaran, hydrofoil & planning vessels may %e used for military and civilian applications #alient features8 •
igh #peed P power ratio
•
igh sta%ility
•
=ood sea !eeping performance
•
=ood stealth features
•
$ow speed loss in waves
SUPER CAVITATIN4 PROPELLERS
Rpm -4++ 0avitation num%er +'; Q L/+ #peed8 L 3+6nots #alient features8 •
ery high5speed cavitation %eyond 3+ !nots
•
•
•
No failure to generate thrust & damage of propeller due to cavitation igh efficiency
SUR3ACE CAVITATIN4 PROPELLER
igh efficiency
•
•
•
No damage of propellers igh5speed application %eyond 3+ !nots
PUMP5ET PROPULSOR
Ultra quiet modern propulsor for su%marine & torpedo applications with e2c ellent cavitation and stealth features #pecifications8 Diameter K;.*mm Rpm -?++ No' of %lades on rotor -> No' of %lades on stator *> Q
?+
#peed8 4+6nots
ery high5speed applications up to ?+!nots
•
igh cavitation inception speeds
•
•
Nominal wa!e & tur%ulence left in slipstream ery high efficiency
Ma.or area of %or& at NSTL
•
0enter of e2cellence for underwater weapon technologies and associated systems'
•
Design, Development, Testing, 1valuation and $eading to production of torpedoes, mines, decoys, targets, simulators and launchers'
•
ctivities on Warship Technology, #tealth Technology and ydro5dynamic research services'
•
Development of 7aterials for 7arine pplications'
•
9leet support activities li!e 1valuation of machinery for their specified shoc! resistance, online vi%ration monitoring and Noise and 7agnetic ranging & analysis'