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This jig is a very wonderful tool that will assist you with regulating a grand piano action away from the piano. If you happen to replace a set of hammers, , hammers, repetitions, this work …Full description
Full description
CFM56-3 REGULATION
THE POWER OF FLIGHT
1 RXCF
04/02/2006
THE POWER OF FLIGHT
CFM56 - 3
2 RXCF
04/02/2006
Speed Governing System Fuel Limiting System Idling System
Main Tasks
VBV VSV HPTCCV
Additional Tasks
MEC
N1 Vs Z
N1 Vs T
Corrections
PMC
CFM 56 - 3 ENGINE OPERATIONAL CONTROL 3 RXCF
04/02/2006
THE POWER OF FLIGHT
N1 Vs P
THE POWER OF FLIGHT
ENGINE OPERATIONAL CONTROL • The CFM56-3 engine control system consists of both: HYDRO MECHANICAL UNIT ELECTRONIC UNIT
Powe Powerr Mana Manage geme ment nt Contr Control ol
– Prov Provid idee FAN FAN sche schedu dulling ing
N1
6 RXCF
04/02/2006
CONTROL SYSTEM SCHEMATIC
7 RXCF
04/02/2006
THE POWER OF FLIGHT
CONTROL SYSTEM SCHEMATIC
THE POWER OF FLIGHT
(Cont’d) N1
ÖFan
Speed
N2
ÖCore
Speed
WF
ÖFuel
Flow
TMC
ÖTorque
PS12
ÖFan
PS3
ÖCompressor
Discharge Pressure
CBP
ÖCompressor
Bleed Pressure
T12
ÖFan
T2.5
ÖHPC
T2
ÖFan
TC1
ÖTurbine
Clearance Control 5Th Stage
TC2
ÖTurbine
Clearance Control 9Th Stage
TC3
ÖTurbine
Clearance Control Timer Signal
Motor Current
Inlet Static Air Pressure
Inlet Total Air Temperature Inlet Inlet Air Temperat Temperature ure
Inlet Temperature
8 RXCF
04/02/2006
ENGINE STATIONS 25
12
HP Co Compressor In Inlet
Secondary Flow Inlet 3
2
THE POWER OF FLIGHT
HP Compr ompreessor ssor Disc ischarg hargee
Primary Flow Inlet
49. 5
Stage 2 LPT Inlet
9 RXCF
04/02/2006
MEC
THE POWER OF FLIGHT
OIL/ FUEL HEAT EXCHANGER MEC
FUEL PUMP 10 RXCF
04/02/2006
THE POWER OF FLIGHT
MEC OPERATION • MEC is an Hydro mechanical device using fuel pressure to work. • A device device monitor monitorss fuel fuel pressure pressure at at low flow flow conditi conditions ons for for MEC servo operation.
FUEL PUMP
BYPASS
LP STAGE
VALVE
MEC Fuel Metering System
FUEL
FUEL
FUEL PUMP
METERING
SHUT-OFF
HP STAGE
VALVE
VALVE
PRESSURISING VALVE 11
RXCF
04/02/2006
MEC PURPOSE
THE POWER OF FLIGHT
• The MEC’s job is divided in 2 tasks: MAIN TASKS: – Speed governing system – Fuel limiting system – Idling system ADDITIONAL TASKS: Control functions to optimise engine performance – VBV – VSV – HPTCCV 12 RXCF
04/02/2006
SPEED GOVERNING SYSTEM
THE POWER OF FLIGHT
MEC SPEED GOVERNING SYSTEM
N2 demand PS12 FMV
T2
N2 actual
Wf
Fuel
13 RXCF
04/02/2006
FUEL LIMITING SYSTEM
THE POWER OF FLIGHT
• During transient transient operation, the speed governing system system could change change the fuel flow beyond the safe limits. • The purpose purpose of of the fuel fuel limiting limiting system system is to to define define and impose impose correct correct engine fuel flow limits during rapid transients:
ACCELERATIONS DECELERATIONS STARTS
14 RXCF
04/02/2006
FUEL LIMITING SYSTEM (Cont’d)
MEC
THE POWER OF FLIGHT
T2.5
FUEL
PS3 SPEED GOVERNING
LIMITING SYSTEM
N2 CBP
SYSTEM
N2 demand PS12 +/-
T2
N2 actual
FMV
Wf
Fuel
15 RXCF
04/02/2006
IDLING SYSTEM
THE POWER OF FLIGHT
HIGH IDLE:
• Used only when anti-icing is selected selected or if a flying aircraft has flaps configuration > 15°. • It is optimised optimised to provide provide rapid recovery of takeoff thrust if required.
LOW IDLE:
• Ground idle:
Provide adequate taxi thrust while minimising noise, fuel consumption and braking effort
•Flight idle:
Scheduled to minimise fuel consumption. 16
RXCF
04/02/2006
IDLING SYSTEM (Cont’d)
MEC DESIRED SPEED SETTING
THE POWER OF FLIGHT
T2.5
FUEL
PS3
AIRCRAFT CONFIGURATION
LIMITING
PLA ID PLA IDLE LE Yes / NO
SYSTEM
N2 CBP
N2 demand PS12 +/-
T2
N2 actual
FMV
Wf
Fuel
17 RXCF
04/02/2006
MEC ADDITIONAL TASKS
THE POWER OF FLIGHT
VBV SYSTEM • VBV VBV syste system m posit position ionss 12 12 valve valvess by by hydraulic pressure acting upon a fuel gear motor. • The fuel fuel pressure pressure is schedu scheduled led by the the MEC. • VBV VBV feedba feedback ck cabl cablee is positi positione oned d to provide provide the MEC with a current current VBV position to compare with the desired position. 18 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VBV SYSTEM (Cont’d)
19 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VBV PURPOSE As the Compressor is optimised for ratings close to maximum power engine operation has to be protected during deceleration d eceleration or at low speed: Without Without VBV installed: installed: At Deceleration Deceleration or Low speed speed ⇒ Booster Booster Outlet Outlet Airflow ↓↓ much more than Booster Pressure Ratio ⇒ LPC LPC stall margin reduced
To re-establish a suitable mass flow VBV are installed on the contour of the primary airflow stream between booster and HPC to download booster exit. With With VBV instal installed: led: Deceleration or Low speed speed At Deceleration ⇒ VBV VBV fully fully ope open n ⇒ Booster Booster Pressure Pressure Ratio ↓↓ but same Booster Outlet Airflow Plenty of LPC stall margin ⇒ Plenty 20 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VBV PURPOSE (Cont’d) B O O S T E R P R E S S U R E R A T I O
TYPICAL TYPICAL LPC LPC FLOW CHART CHART
1
Acceleration Schedule
5
If VBV VBV not clos closed ed
3
Deceleration Schedule
4
If VBV VBV not open open
2
Operating Line
Efficiency Maxi Efficiency Design Point
3
MCT
STALL REGION
ISO N1 Line
2 4
VBV Operation
5 IDLE
1
LOW EFFICIENCY REGION
• Low speed or Deceleration VBV VBV OPEN OPEN
• High speed or acceleration BOOSTER OUTLET AIRFLOW
VBV VBV CLOS CLOSED ED 21
RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VSV SYSTEM VSV system system change changess the angle of the HP Compress Compressor or IGV and N° 1,2 and 3 stator stator stage stagess according according to the the MEC computation. MEC directs a resulting high pressure fuel flow to the dual VSV
actuators. The actuators mechanically position the VSV. A feedback feedback cable cable provides provides the VSV VSV position position to the MEC. A comparison is performed between schedule requirements and actual VSV position to determine the the need to to continue actuator control or not. 22 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VSV SYSTEM (Cont’d)
23 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VSV SYSTEM (Cont’d)
24 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VSV PURPOSE • The Compressor is optimised for ratings close to maximum power. • Engine Engine operation operation has to be protected protected during during deceleration or at low speed. • VSV system system position position HPC HPC Stator Stator Vanes to the the appropriate angle of incidence. VSV VSV (3) (3)
IGV
- VSV VSV opti optimi mise se HPC effic efficie ienc ncy. y.
ROTOR
improve stall stall margi margin n for - VSV improve transient engine operations.
VSV 1
Etc … ROTOR STAGE IGV (Inlet Guide Vane) 25 RXCF
04/02/2006
MEC ADDITIONAL TASKS (Cont’d)
THE POWER OF FLIGHT
VSV PURPOSE (Cont’d) C O M P R E S S O R
TYPICA TYPICAL L HPC HPC FLOW FLOW CHART CHART
Efficiency
1
Acceleration Schedule
2
If VSV VSV not open open
3
Deceleration Schedule
4
Operating Line
2 1
P R E S S U R E
Maxi Efficiency Design Point MCT
STALL REGION
ISO N1 Line
VSV Operation
4
R A T I O
• Low speed or Deceleration 3
IDLE
LOW EFFICIENCY REGION
VSV VSV CLOSE CLOSED D
• High speed or acceleration COMPRESSOR OUTLET AIRFLOW
VSV VSV OPEN OPEN 26
RXCF
04/02/2006
CLEARANCE CONTROL
THE POWER OF FLIGHT
Operating tip clearance in the core engine are of primary importance. They determine:
•
Steady state efficiencies: ⇒
Fuel consumption
Transient engine performance: Peak gas temperature ⇒ Compressor stall margin ⇒
27 RXCF
04/02/2006
CLEARANCE CONTROL (Cont’d) •
THE POWER OF FLIGHT
Clearance Control in the CFM56 CFM56 engine is accomplished by a combination combination of
3 mechanical designs: Passive control:
Using materials in the compressor aft case with low coefficient of thermal expansion.
⇒
Forced cooling:
Using Low Pressure Booster discharge cooling air for compressor and turbine.
⇒
Automatic control:
HPTCC HPTCC VALVE VALVE and and HPTCC HPTCC TIMER TIMER are are used used to contr control ol the the tip clearance clearance between HPT blades and and stationary stationary tip shrouds. shrouds. ⇒
28 RXCF
04/02/2006
HPTCCV ACTUATION •
THE POWER OF FLIGHT
Automatic Control is using Bleed Air from 5 Th and 9Th stages of
HPC to eith either er cool cool or heat heat the HPT shroud shroud.. AIR FROM
N2 > 95 %
5Th
YES / NO
MEC
HPTCC TIMER
AIRCRAFT ON THE GROUND
YES / NO
STAGE
HPTCC VALVE
HPT SHROUD
AIR FROM 9Th
STAGE
29 RXCF
04/02/2006
HPTCCV ACTUATION (Cont’d) •
THE POWER OF FLIGHT
During flight:
- Air selection selection is determine determined d by fuel pressure pressure signals signals sent sent from the MEC to the TIMER. - The TIMER TIMER sends sends fuel fuel pressu pressure re signals signals without change to actuat actuatee the the HPTCC HPTCC VALVE. VALVE. - The selected selected bleed bleed air is ducted ducted to a manifold manifold surroundin surrounding g the HPT HPT SHROU HROUD. D. 30 RXCF
04/02/2006
HPTCCV ACTUATION (Cont’d) •
THE POWER OF FLIGHT
During takeoff:
- The TIMER overrides overrides the the normal normal MEC operation operation of of the valve. valve. - It is seque sequencin ncing g a transien transientt air schedu schedule le over over a specifi specified ed time time period period to maintain a more nearly constant constant HPT blade tip clearance during the period period of HPT Rotor/Stat Rotor/Stator or thermal thermal stabilisati stabilisation. on. - This maintain maintain Turbine Turbine efficiency efficiency and and decreases decreases transient transient EGT overshoot. - A lockout valve permits permits the TIMER TIMER to actuate actuate only once per per engine cycle. ( i.e. from start to shut down) 31 RXCF
04/02/2006
HPTCCV ACTUATION (Cont’d)
THE POWER OF FLIGHT
32 RXCF
04/02/2006
HPTCCV ACTUATION (Cont’d)
THE POWER OF FLIGHT
• The TIMER SEQUENCE: - Starting Starting Referen Reference ce Point Point is when the engin engine e reach 95 % N2. - Then:
0 to 8 s
⇒
No air
8 to 152 s
⇒
5Th stage air
152 to 182 s
⇒
5Th + 9Th stage air
33 RXCF
04/02/2006
HPTCCV ACTUATION (Cont’d) NO TIMER
THE POWER OF FLIGHT
TIMER STATOR Ø
ROTOR Ø CLEARANCE with TIMER
No Air
0s
5Th 5Th stage stage Air Air
8s
5+9Th stage Air
152 s
182 s
CLEARANCE without TIMER 34 RXCF
04/02/2006
PMC INPUT POWER
THE POWER OF FLIGHT
COCKPIT SW: Ö
PMC PMC On / Off Off
PS12
INPUT SIGNALS: Ö
N1, T12, PLA
OUTPUT SIGNALS: Ö
FOR MEC MEC TORQUE TORQUE MOTOR MOTOR
MONITOR CONNECTION 35 RXCF
04/02/2006
PMC PURPOSE
THE POWER OF FLIGHT
• In a high bypass engine, total thrust is more accurately controlled by controlling N1 speed.
FAN is 80% of the POWER !
This is accomplished by vary varyiing N2 spe speed
to reach the accurate N1 speed . 36 RXCF
04/02/2006
PMC OPERATION •
THE POWER OF FLIGHT
The main main goal goal of of the PMC is to make pilot’s job more
comfortable. •
PMC is performing performing automa automaticall tically y 3 corrections corrections::
N1 Vs ALTITUDE N1 Vs PRESSURE
N1 Vs TEMPERATURE 37 RXCF
04/02/2006
PMC OPERATION (Cont’d)
THE POWER OF FLIGHT
N1 Vs ALTITUDE
• As the altitude is increasing, if you want to keep a steady thrust %, you need to increase N1. PMC ON
PMC increa increase se N1
N1
⇒
PLA remain remain unchang unchanged. ed.
STEADY THRUST %
PMC OFF
The PILOT must increase N1 ⇒ PLA change change..
Z 38 RXCF
04/02/2006
PMC OPERATION (Cont’d)
THE POWER OF FLIGHT
N1 Vs PRESSURE
• As the pressure is decreasing, if you want to keep a steady thrust %, you need to increase N1. PMC ON
STEADY THRUST %
N1
PMC increa increase se N1 ⇒
PLA remain remain unchang unchanged. ed.
PMC OFF
The PILOT must increase N1 ⇒ PLA change change..
P 39 RXCF
04/02/2006
PMC OPERATION (Cont’d) N1 Vs TEMPERATURE N1
• At
MAX THRUST
T EGT
THE POWER OF FLIGHT
CORNER POINT TEMPERATURE
T
takeoff, to get the max thrust (flat rated thrust) as temperature increases, N1 and EGT EGT must also increase. increase. • But mechanica mechanicall limitations limitations impose impose a limit which is a temperature called: “Corner “Corner Point” Point” or “Flat “Flat Rated Rated Temperature”.
Beyond it: PMC ON PMC is limiting N1 and EGT
PMC OFF The PILOT must limit N1 and EGT 40
RXCF
04/02/2006
PMC OPERATION (Cont’d)
THE POWER OF FLIGHT
• PMC efficiency start at 50% N1 and is fully efficient at or above 70% N1. PMC tr trim imss MEC MEC to maintain the commanded thrust • PMC
• Schedule N1 is compared to actual N1.The error signal generates generates from from the PMC PMC an Output Output Current Current (TMC) to a torque torque motor mounted on the MEC. The torque motor changes Fuel Flow (Wf). Ì N2 and N1 change. 41 RXCF
