CFM56-3 ENGINE REGULATION - · PDF fileMETERING VALVE PRESSURISING VALVE FUEL SHUT-OFF VALVE BYPASS ... SPEED SETTING FMV Fuel Wf T2 N2 demand ... by controlling N1 speed. FAN

THE POWER�OF FLIGHT

104/02/2006RXCF

CFM56CFM56--3 REGULATION3 REGULATION


204/02/2006RXCF

CFM56CFM56 -- 33


304/02/2006RXCF

ENGINE OPERATIONAL CONTROLENGINE OPERATIONAL CONTROL

MECMEC PMCPMC

Main Tasks Additional Tasks

Speed Governing System

Idling System

Fuel Limiting System

VBV

VSV

HPTCCV N1 Vs Z

N1 Vs P

N1 Vs T

Corrections

CFMCFM 56 56 -- 33


404/02/2006RXCF

ENGINE OPERATIONAL ENGINE OPERATIONAL CONTROLCONTROL

• The CFM56CFM56--33 engine control system consists of both:

HYDRO MECHANICAL UNIT

ELECTRONIC UNIT


504/02/2006RXCF

HYDRO MECHANICAL UNITHYDRO MECHANICAL UNIT

–– WFWF ( Fuel Flow )–– VBVVBV ( Variable Bleed Valve )–– VSVVSV ( Variable Stator Vane )–– HPTCCVHPTCCV ( High Pressure Turbine Clearance

Control Valve )

• MECMECAutomatically schedules:

N2

Main Engine Control


604/02/2006RXCF

ELECTRONIC UNITELECTRONIC UNIT

•• PMCPMC Power Management Control

– Provide FAN scheduling N1


704/02/2006RXCF

CONTROL SYSTEM SCHEMATIC CONTROL SYSTEM SCHEMATIC


804/02/2006RXCF

CONTROL SYSTEM SCHEMATIC CONTROL SYSTEM SCHEMATIC (Cont(Cont’’d)d)

N1 Fan Speed

N2 Core Speed

WF Fuel Flow

TMC Torque Motor Current

PS12 Fan Inlet Static Air Pressure

PS3 Compressor Discharge Pressure

CBP Compressor Bleed Pressure

T12 Fan Inlet Total Air Temperature

T2.5 HPC Inlet Air Temperature

T2 Fan Inlet Temperature

TC1 Turbine Clearance Control 5Th Stage

TC2 Turbine Clearance Control 9Th Stage

TC3 Turbine Clearance Control Timer Signal


904/02/2006RXCF

ENGINE STATIONSENGINE STATIONS

2 Primary Flow Inlet

12 Secondary Flow Inlet

25 HP Compressor Inlet

3 HP Compressor Discharge

49. 5 Stage 2 LPT Inlet


1004/02/2006RXCF

MECMEC

MEC

FUEL PUMP

OIL/ FUEL HEAT

EXCHANGER


1104/02/2006RXCF

MECMEC OPERATIONOPERATION• MEC is an Hydro mechanical device using fuel pressure to work.• A device monitors fuel pressure at low flow conditions for MECservo operation.

FUEL

METERING

VALVEPRESSURISING PRESSURISING

VALVEVALVE

FUEL

SHUT-OFF

VALVE

BYPASS

VALVE

FUEL PUMP

HP STAGE

FUEL PUMP

LP STAGE MEC Fuel Metering System


1204/02/2006RXCF

MECMEC PURPOSEPURPOSE• The MECMEC’’ss job is divided in 2 tasks:

MAIN TASKS:

ADDITIONAL TASKS:

–– Speed governing systemSpeed governing system–– Fuel limiting systemFuel limiting system–– Idling systemIdling system

–– VBVVBV

– VSVVSV

– HPTCCVHPTCCV

Control functions to optimise engine performance


1304/02/2006RXCF

SPEED GOVERNING SYSTEMSPEED GOVERNING SYSTEM

SPEED

GOVERNING

SYSTEM

FMV Wf

N2 demand

N2 actualT2 Fuel

PS12

MEC


1404/02/2006RXCF

FUEL LIMITING SYSTEMFUEL LIMITING SYSTEM

• During transient operation, the speed governing system could change the fuel flow beyond the safe limits.• The purpose of the fuel limiting system is to define and impose correct engine fuel flow limits during rapid transients:

ACCELERATIONS

DECELERATIONS

STARTS


1504/02/2006RXCF

SPEED

GOVERNING

SYSTEM

FMV

Fuel

Wf

T2

N2 demand

N2 actual

FUEL

LIMITING

SYSTEM

PS12

MEC

FUEL LIMITING SYSTEM FUEL LIMITING SYSTEM (Cont(Cont’’d)d)

+ / -

N2

PS3

T2.5

CBP


1604/02/2006RXCF

IDLING SYSTEMIDLING SYSTEM

HIGH IDLE:

LOW IDLE:

• Used only when anti-icing is selected or if a flying aircraft has flaps configuration > 15°.• It is optimised to provide rapid recovery of takeoff thrust if required.

• Ground idle:

•Flight idle:

Provide adequate taxi thrust while minimising noise, fuel consumption and braking effort

Scheduled to minimise fuel consumption.


1704/02/2006RXCF

DESIRED

SPEED

SETTING

FMV

Fuel

Wf

T2

N2 demand

N2 actual

+ / -

FUEL

LIMITING

SYSTEM

PS3

N2

T2.5

CBP

PS12

MEC

PLA IDLEYes / NO

AIRCRAFT CONFIGURATION

IDLING SYSTEM IDLING SYSTEM (Cont(Cont’’d)d)


1804/02/2006RXCF

MECMEC ADDITIONAL TASKSADDITIONAL TASKS

VBVVBV SYSTEMSYSTEM

• VBV system positions 12 valves by hydraulic pressure acting upon a fuel gear motor.

• The fuel pressure is scheduled by the MEC.

• VBV feedback cable is positioned to provide the MEC with a current VBVposition to compare with the desired position.


1904/02/2006RXCF

MECMEC ADDITIONAL TASKS ADDITIONAL TASKS (Cont(Cont’’d)d)

VBVVBV SYSTEM SYSTEM (Cont(Cont’’d)d)


2004/02/2006RXCF


VBVVBV PURPOSEPURPOSE

As the Compressor is optimised for ratings close to maximum power engine operation has to be protected during deceleration or at low speed:

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.

Without VBV installed:At Deceleration or Low speed⇒ Booster Outlet Airflow ↓↓ much more than Booster Pressure Ratio⇒ LPC stall margin reduced

With VBV installed:At Deceleration or Low speed⇒ VBV fully open⇒ Booster Pressure Ratio ↓↓ but same Booster Outlet Airflow⇒ Plenty of LPC stall margin


2104/02/2006RXCF


VBVVBV PURPOSE PURPOSE (Cont(Cont’’d)d)

Maxi EfficiencyDesign Point

ISO N1 Line

Efficiency ↓↓

BOOSTER OUTLET AIRFLOW

BOOSTER

PRESSURE

RATIO

LOW EFFICIENCYREGION1

2

3

4VBVOperation

Acceleration Schedule 1

2

3

4

• Low speed or Deceleration⇒ VBV OPEN

• High speed or acceleration⇒ VBV CLOSED

TYPICAL LPC FLOW CHART

5

5

Operating Line

Deceleration Schedule

If VBV not open

If VBV not closed

STALLREGION

IDLE

MCT


2204/02/2006RXCF


VSVVSV SYSTEMSYSTEM

VSV system changes the angle of the HP Compressor IGV and N° 1,2 and 3 stator stages according to the MEC computation.MEC directs a resulting high pressure fuel flow to the dual VSVactuators.The actuators mechanically position the VSV.

A feedback cable provides the VSV position to the MEC.

A comparison is performed between schedule requirements and actual VSV position to determine the need to continue actuator control or not.


2304/02/2006RXCF


VSVVSV SYSTEMSYSTEM (Cont(Cont’’d)d)


2404/02/2006RXCF


VSVVSV SYSTEMSYSTEM (Cont(Cont’’d)d)


2504/02/2006RXCF

IGV

ROTOR

VSV 1

Etc …


VSVVSV PURPOSEPURPOSE

IGV (Inlet Guide Vane)

ROTOR STAGE

VSV (3)

- VSV optimise HPC efficiency.- VSV improve stall margin for transient engine operations.

• The Compressor is optimised for ratings close to maximum power.• Engine operation has to be protected during deceleration or at low speed.• VSV system position HPC Stator Vanes to the appropriate angle of incidence.


2604/02/2006RXCF


VSVVSV PURPOSE PURPOSE (Cont(Cont’’d)d)

COMPRESSOR OUTLET AIRFLOW

COMPRESSOR

PRESSURE

RATIO

LOW EFFICIENCYREGION

STALLREGION

Efficiency ↓↓

Maxi EfficiencyDesign Point

ISO N1 Line

VSVOperation

1

4

2

TYPICAL HPC FLOW CHARTAcceleration Schedule 1

2

3

4 Operating Line

Deceleration Schedule

If VSV not open

• Low speed or Deceleration⇒ VSV CLOSED

• High speed or acceleration⇒ VSV OPEN

3IDLE

MCT



2704/02/2006RXCF

CLEARANCE CONTROLCLEARANCE CONTROL

• 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


2804/02/2006RXCF

CLEARANCE CONTROL CLEARANCE CONTROL (Cont(Cont’’d)d)

• Clearance Control in the CFM56 engine is accomplished by a 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 VALVE and HPTCC TIMER are used to control the tip clearance between HPT blades and stationary tip shrouds.


2904/02/2006RXCF

HPTCCVHPTCCV ACTUATIONACTUATION

• Automatic Control is using Bleed Air from 5Th and 9Th stages of HPC to either cool or heat the HPT shroud.

MEC HPTCC TIMER HPT SHROUD

AIR FROM

5Th

STAGE

AIR FROM

9Th

STAGE

AIRCRAFT ON THE

GROUNDYES / NO

N2 > 95 %YES / NO

HPTCCVALVE


3004/02/2006RXCF

HPTCCVHPTCCV ACTUATION ACTUATION (Cont(Cont’’d)d)

• During flight:

- Air selection is determined by fuel pressure signals sent from the MEC to the TIMER.

- The TIMER sends fuel pressure signals without change to actuate the HPTCC VALVE.

- The selected bleed air is ducted to a manifold surrounding the HPT SHROUD.


3104/02/2006RXCF


• During takeoff:

- The TIMER overrides the normal MEC operation of the valve.

- It is sequencing a transient air schedule over a specified time period to maintain a more nearly constant HPT blade tip clearance during the period of HPT Rotor/Stator thermal stabilisation.

- This maintain Turbine efficiency and decreases transient EGTovershoot.

- A lockout valve permits the TIMER to actuate only once per engine cycle. ( i.e. from start to shut down)


3204/02/2006RXCF



3304/02/2006RXCF


• The TIMER SEQUENCE:

- Starting Reference Point is when the engine reach 95 % N2.

0 to 8 s ⇒ No air

8 to 152 s ⇒ 5Th stage air

152 to 182 s ⇒ 5Th + 9Th stage air

- Then:


3404/02/2006RXCF


0 s 8 s 152 s 182 s

No Air 5+9Th stage Air5Th stage Air

NO TIMER TIMER

STATOR Ø

ROTOR Ø

CLEARANCE with TIMER

CLEARANCE without TIMER


3504/02/2006RXCF

PMCPMC

INPUT POWER

INPUT SIGNALS:

N1, T12, PLA

OUTPUT SIGNALS:

FOR MEC TORQUE MOTOR

MONITOR CONNECTION

COCKPIT SW:

PMC On / Off

PS12


3604/02/2006RXCF

PMCPMC PURPOSEPURPOSE

• In a high bypass engine, total thrust is more accurately controlled by controlling N1 speed.

FAN is 80% of the POWER !FAN is 80% of the POWER !

This is accomplished byvarying N2 speed

to reach theaccurate N1 speed.


3704/02/2006RXCF

PMCPMC OPERATIONOPERATION

• The main goal of the PMC is to make pilot’s job morecomfortable.

• PMC is performing automatically 3 corrections:

N1 Vs ALTITUDE

N1 Vs PRESSURE

N1 Vs TEMPERATURE


3804/02/2006RXCF

N1N1 Vs Vs ALTITUDEALTITUDE

PMCPMC OPERATION OPERATION (Cont(Cont’’d)d)

N1

Z

STEADYTHRUST %

• As the altitude is increasing, if you want to keep a steady thrust %, you need to increase N1.

PMC OFFThe PILOT must increase N1⇒ PLA change.

PMC ONPMC increase N1

⇒ PLA remain unchanged.


3904/02/2006RXCF


N1N1 Vs Vs PRESSUREPRESSURE

N1

P

STEADYTHRUST %

• As the pressure is decreasing, if you want to keep a steady thrust %, you need to increase N1.

PMC ONPMC increase N1

⇒ PLA remain unchanged.

PMC OFFThe PILOT must increase N1⇒ PLA change.


4004/02/2006RXCF


N1N1 Vs Vs TEMPERATURETEMPERATURE

N1 MAX THRUST

EGT

T

CORNER POINTTEMPERATURE

T

• At takeoff, to get the max thrust (flat rated thrust) as temperature increases, N1 and EGT must also increase.• But mechanical limitations impose a limit which is a temperature called: “Corner Point” or “Flat Rated Temperature”.

Beyond it:

PMC ONPMC is limiting N1 and EGT

PMC OFFThe PILOT must limit N1 and EGT


4104/02/2006RXCF


• PMC efficiency start at 50% N1 and is fully efficient at or above 70% N1.

• PMC trims MEC to maintain the commanded thrust

• Schedule N1 is compared to actual N1.The error signalgenerates from the PMC an Output Current (TMC) to a torque motor mounted on the MEC.The torque motor changes Fuel Flow (Wf).

N2 and N1 change.


4204/02/2006RXCF


N1 / ZCORRECTION

N1 / PCORRECTION

N1 / TCORRECTION

SCHEDULE N1

ENGINE MEC

TORQUE MOTOR

ACTUAL N1

PMC

PLA

PMC on / off

Wf


4304/02/2006RXCF

THE ENDTHE END

THANKS FOR YOURTHANKS FOR YOURATTENTION !ATTENTION !

Documents

CFM56-3 ENGINE REGULATION - · PDF fileMETERING VALVE PRESSURISING VALVE FUEL SHUT-OFF VALVE BYPASS ... SPEED SETTING FMV Fuel Wf T2 N2 demand ... by controlling N1 speed. FAN