A NORMALIZED CONTROL SYSTEM FOR A TURBOJET ENGINE

A NORMALIZED CONTROLSYSTEM FOR A TURBOJETENGINEOri Yekutiel, Yinon AmirRAFAEL Ltd- P.O.B 2250 (39)Haifa 31021, Israel6 th Symposium on Jet Engines and Gas TurbinesNovember 2006RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 1

APPROACH:– Normalization of fuel flow and RPMu correction for altitude, mach, DISA, andlinearization– Normalize Measurements– Design single controller (for(all flightconditions)– "de-normalizenormalize” output (normalized fuelflow) and apply to engineRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 2

FEATURES:uEnginenormalizationsimplifies control systemdesign for all control designapproachesuOnly a simple PI exampleincluded in presentationRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 3

A PREVIOUS CONTROLLER(1/5)uGAIN SCHEDULING (Mach,Altitude(Mach,Altitude,RPM)uRequires Tables – extensive testingfor modeling and verificationuLimited use of knowledge of thephysical engine behaviorRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 4

A PREVIOUS CONTROLLER(2/5)RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 5

A PREVIOUS CONTROLLER(3/5)P2, T2, T5XDUCERSRPM comCOMMANDLIMITERACCELERATIONLIMITER+-errorCONTROLLER( P I )Wf com[Volt]AMPLIFIER&PUMPWf com[g/s]ENGINERPMMIN/MAX RPMBW, ACCELsatlo, sathiPUMP RPMXDUCERRPM XDUCERMach, AltitudeLIMITERRPM,...RPMT5CUTOFFELECTRONICINTERFACEUNITOther Telemetry Data(Temperatures, Pressures, ...)RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 6

A PREVIOUS CONTROLLER(4/5)RPM comRPM measCTRLLRPI RPM2Wfcom Wfcom2RPMENGINEENGINEDYNAMICS(GAIN=1)LIMITRPMMeasurementRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 7

A PREVIOUS CONTROLLER(5/5)RPM comRPM measK1 + I1s11 + s τ engOLLIMIT1K Iτ engRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 8

THE NORMALIZED CONTROLLERu T0 = 288.15u TISA= T0 - 0.0065 * Altu Tamb= TISA + DISAu Beta = 1+ ( Mach ^ 2 ) / 5u Ttot= Tamb * Betau Delta= ( ( TISA / T0 )^5.256 ) * Beta^3.5u = Ptot/P0u Theta= Ttot / T0u RPM*= RPM / Sqrt ( Theta )u Wf*= Wf / ( Delta * Sqrt ( Theta ) )RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 9

THE CONCEPT:M, H, DISA5M 4Engine with normalized controller1RPMcomC RPM TJC TJNormalizationC TJRPMcom * e Wf ' Wf Mach Wf * WfRPMcom * RPM MachWfPICorrectionLIMITER Correctionde-normalizationinverseC TJTauWf-TagLIMITERC TJDynamics6M, H, DISAWf ' (RPM *)RPM MachCorrectionC TJRPM *RPMNormalizationC TJRPMENGINEM 3M, H, DISA2red: physical normalization (valid for all engines);cyan: Engine-dependent blocks (note: only 2 differenttypes)yell: PI parameters, per individual controller requirement(BW, Disturbance Rejection, …).RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 10

FEATURES (1/2):uGain is practically constant and unityover RPM, altitude, mach and DISAuA single gain P and Fuel Flow limitscan be designed.uOther Controller designs (not PI) alsosimplified (no, or less, envelopedependence)RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 11

FEATURES (2/2):u Integral Gain I is dependent on engine dynamics.u A mach-AltitudeAltitude-RPM table may be used (as inthe Present Solution)u Alternately a model of Corrected Tau can beexplored.– Otto, E.W. and Taylor, B.L, "Dynamics of a Turbojet Engine Consideredas a Quasi-Static System," NACA TR 1011, 1951.RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 12

uOBJECTIVES:FUEL LIMITER:Avoid surge, stall, over-temperature,blowoutuDESIGN:In normalized controller !!uIMPLEMENTATION (PI case):Include anti-windupRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 13

SIMULATION RESULTS (1/2):RPM [%]10080RPM C.L. Step response: Full envelope0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9RPM COMRPM-MeasRPM [%]9972RPM C.L. Step response: Full envelope0.6 0.62 0.64 0.66 0.68 0.7 0.72 0.74RPM COMRPM-MeasNorm Wf [%]Norm. envelope1005001000-1000.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Sat-HighSat-LowWf-Tag0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Normalized timeMach [%]Alt [%]DeltaISA: -100 -> 100 [%]Norm Wf [%]Norm. envelope106.55.51000-1000.6 0.62 0.64 0.66 0.68 0.7 0.72 0.74Sat-HighSat-LowWf-Tag0.6 0.62 0.64 0.66 0.68 0.7 0.72 0.74Normalized timeMach [%]Alt [%]DeltaISA: -100 -> 100 [%]RAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 14

SIMULATION RESULTS (2/2):(Increased gain !!)Pressure Ratio: P03/P02 [%]100908070605040COMPRESSOR MAP.M=0 [%] ; H=0[%]; DISA=0[K];Steady-State LineCorrected RPM [%]100Surge Line91SM = 5% Line827364 response55473020 30 38 40 50 60 70 80 90 100Corrected Air Mass Flow [%]RPM [%]Norm Wf [%]1008060RPM C.L . Step response: M=0 [%] ; H=0[%]; DISA=0[K];RPM COMRPM-Meas400 0.2 0.4 0.6 0.8 110.5Sat-HighSat-LowWf-Tag00 0.2 0.4 0.6 0.8 1Normalized timeRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 15

BENEFITS of the APPROACH:u good physical basis for designu simple controller - single designu simple limiter - single designu easier testability - fewer envelope pointsu simpler transportability of the controller toother enginesRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 16

THANK YOUJRAFAEL Ltd.A NORMALIZED CONTROL SYSTEM for a TURBOJET ENGINE 17