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The Aircraft Engine Design Project Fundamentals of Engine …

GE Aircraft EnginesgGE AviationThe Aircraft Engine Design Project Fundamentals of Engine CyclesKen GouldPhil WeedSpring 20091GE Aircraft EnginesgGE Aviation Technical HistoryGE Aviation Technical jet turboprop engineVibl ttiVariable stator engineMach 2 fighter engineMach 3 bomber engineHigh bypass engineVariable cycle turbofan engineUnducted fan engineI-A - First jet engineGE90 on test(Developed in Lynn, MA, 1941)Unducted fan engine30:1 pressure ratio engineDemonstration of 100k+ Engine thrustCertified double annular combustor engineFirst turboprop powered Aircraft , Dec. 19452T L I K O P F T L I K O P F GE Aircraft EnginesgFlowdown of RequirementsThe Customer: Overall system requirementsMTOW, Range, Cost per seat per mileThe Airframer: Sub-system requirementsTechnical: Wing (lift/drag),Engines(Thrust/SFC)CSProgram :Cost and ScheduleFAA/JAAE ngines Systems: Module requirementsff

X XX X Design Considerations Process Centering and Variation X XX X XXX X X X X X X X On-Target X X Reduce Spread Center Process X X X X X XXXXXX X Six Sigma Methodology Applies Statistical Analyses to Center 17 ggypp y Processes and Minimize Variation General Electric Aircraft Engines.

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Transcription of The Aircraft Engine Design Project Fundamentals of Engine …

1 GE Aircraft EnginesgGE AviationThe Aircraft Engine Design Project Fundamentals of Engine CyclesKen GouldPhil WeedSpring 20091GE Aircraft EnginesgGE Aviation Technical HistoryGE Aviation Technical jet turboprop engineVibl ttiVariable stator engineMach 2 fighter engineMach 3 bomber engineHigh bypass engineVariable cycle turbofan engineUnducted fan engineI-A - First jet engineGE90 on test(Developed in Lynn, MA, 1941)Unducted fan engine30:1 pressure ratio engineDemonstration of 100k+ Engine thrustCertified double annular combustor engineFirst turboprop powered Aircraft , Dec. 19452T L I K O P F T L I K O P F GE Aircraft EnginesgFlowdown of RequirementsThe Customer: Overall system requirementsMTOW, Range, Cost per seat per mileThe Airframer: Sub-system requirementsTechnical: Wing (lift/drag),Engines(Thrust/SFC)CSProgram :Cost and ScheduleFAA/JAAE ngines Systems: Module requirementsfffFAA/JAAS afety/reliabilityNoise/emissionsQualifie d ProductTechnical: Pressure ratio, efficiency, weight, lifeProgram.

2 NRE, part cost, schedule, validation plan3 Design & ValidationGE Aircraft EnginesgThe Aircraft Engine Design ProjectHPT CombustorThe Aircraft Engine Design Project Fundamentals of Engine CyclesCompressorCombustorExhaustTbjtE iairflow4 Turbojet EngineInletGE Aircraft EnginesgEngine Modules and ComponentsTurbojet StationsCompressorEngine Modules and ComponentsCombustorHPT Inlet Exit HP SpoolTurbojet Engine Cross-Section234590jgMulti-stage compressor module5powered by a single stage turbineGE Aircraft EnginesgIdeal Brayton Cycle: T-S RepresentationHP Turbine Inlet4 Expansion5 pressure available forTurbine Exit Pressure5 TCombustorInletAmbient Pressure pressure available forexpansion across Exhaust Nozzle021hWP =Note: 1) Flight Mach = 02) P=PCompression3 WLines of Constant Pressure2) Pt2= Pamb3) P = power4) W = mass flow rate5) h0= total enthalpy Compressor Inlet26 SGE Aircraft EnginesgReal Brayton Cycle.

3 T-S RepresentationHP Turbine InletExpansion4 Turbine Exit Pressure5 pressure available forT3 pressure available forexpansion across Exhaust Nozzle021hWP =Ambient Pressure CombustorInletCompressionImpact of Real Efficiencies:Decreased Thrust @ if T4 is maintainedW2 OrIncrease Temp (fuel flow) to maintain thrust! Lines of Constant PressureCompressor Inlet27 SGE Aircraft EnginesgEngine InletJet Engine Cycle AnalysisEngine Inlet Flow capacity (flow function relationship)Starting with the conservation of mass and substituting the total to ggstatic relations for Pressure and Temperature, can derive:W= Density * Area* VelocityW*(sqrt(Tt)) = M *sqrt(gc* /R) Pt* Ae [1+ (( -1)/2)*M2]( +1)/[2*( -1)]where M is Mach numberTt is total temperature (deg R)Pt is total pressure (psia)f(/)TurbojetW is airflow (lbm/sec)Ae is effective area (in2)gc is gravitational constant= lbm ft/(sec2lbf) is ratio of specific heatsCompressorCombustorHPT HP SpoolInlet Exit 8 is ratio of specific heatsR is gas constant (ft-lbf)/(lbm-deg R)

4 234590GE Aircraft EnginesgCompressorJet Engine Cycle AnalysisCompressor From adiabatic efficiency relationship compressor= Ideal Work/ Actual Work = Cp*(Texit Tinlet)Cp*(Texit Tinlet)=(Pexit/Pinlet)( -1)/ -1 (Pexit/Pinlet)1 Texit/Tinlet - 1where Pexitis compressor exit total pressure (psia)Pinletis compressor exit total pressure (psia)Pinletis compressor exit total pressure (psia)Tinletis compressor inlet total temperature (deg R)Texitis compressor exit total temperature (deg R)Texit is ideal compressor exit temperature (deg R)TurbojetCompressorCombustorHPT HP SpoolInlet Exit 9234590GE Aircraft EnginesgCombustorJet Engine Cycle AnalysisCombustor From Energy balance/ Combustor efficiency relationship.

5 Combustor= Actual Enthalpy Rise/ Ideal Enthalpy Rise= (WF + W)*CpcombustorTe x i t W * C pcombustorTinletWF*FHVWF FHVwhere W is airflow (lbm/sec)WF is fuel flow (lbm/sec)FHV is fuel heating value (BTU/lbm)Tinletis combustor inlet total temperature (deg R)Texitis combustor exit total temperature (deg R)Cp is combustor specific heatBTU/(lbm-deg R)TurbojetBTU/(lbmdeg R)Can express WF/W as fuel to air ratio (FAR)CompressorCombustorHPT HP SpoolInlet Exit 10234590GE Aircraft EnginesgTurbineJet Engine Cycle AnalysisTurbine From efficiency relationship = Actual Work/Ideal Work= Cp*(TinletTe x i t ) turbine= Actual Work/Ideal Work = Cp (Tinlet Te x i t )Cp*(Tinlet Texit )= 1 - (Texit/Tinlet)1(P it/Pi l t)(1)/1 -(Pexit/Pinlet)( -1)/ Work Balance.

6 From conservation of energyTurbine Work = Compressor Work + Losses(W+ WF)* C*(TiltTit)|W*C*(T itTilt)|(W+ WF)* Cpturb* (Tinlet -Texit)|turb= W * Cpcompressor* (Texit -Tinlet)|compwhere Pexitis turbine exit total pressure (psia)Turbojetp(p)Pinletis turbine exit total pressure (psia)Tinletis inlet total temperature (deg R)Texitis exit total temperature (deg R)Texit is ideal exit total temperature (deg R)Cp is specific heat for turbine or compressorCompressorCombustorHPT HP SpoolInlet Exit 11Cp is specific heat for turbine or compressorBTU/(lbm-deg R)234590GE Aircraft EnginesgJet Engine Cycle AnalysisNozzle Isentropic relationship, can determine exhaust propertiesppppTt/Ts= (Pt/Ps)( -1)/ = 1 + (( -1)/2) * M2 From Mach number relationship can determine exhaust velocityv= M*awhere a, speed of sound= sqrt( *gc*R*Ts)whereTt is total temperature (deg R)Pt is total pressure (psia) Ps is static pressure (psia)Ts is static temp (deg R)gis gravitational constantTurbojetgc is gravitational constant= lbm ft/(sec2lbf) is ratio of specific heatsR is gas constant (ft-lbf)/(lbm-deg R)v is flow velocity (ft/sec)

7 CompressorCombustorHPT HP SpoolInlet Exit 12y()a is speed of sound (ft/sec)M is Mach number234590GE Aircraft EnginesgEi PfJet Engine Cycle AnalysisEngine Performance Thrust relationship: from conservation of momentumFnet = W9 V9/ gc-W0 V0/ gc+ (Ps9-Ps0) A9If flight Mach number is 0, v0 = 0and if nozzle expands to ambient, PS9=Ps0 andp,Fnet = W9 V9/ gcwhere gcis gravitational constant Specific Fuel Consumption (SFC)SFC = Wf/ Fnet (lbm/hr/ lbf)(lSFC i b tt )Turbojet(lower SFC is better)CompressorCombustorHPT HP SpoolInlet Exit 13234590GE Aircraft EnginesgA/B / V i bl E ht NlModern Afterburning Turbofan Engine3-stage fan moduleSingle-stage HPT moduleA/B w/ Variable Exhaust NozzlegSingle Stage LPT modulemulti-stage compressor moduleTypical Operating Parameters:OPR25 1 Terms.

8 Annular Combustor14 OPR25 lbm/secThrust Class16K-22K lbfTerms:bladerotating airfoilvanestatic airfoilstagerotor/stator pairPLApilot s throttleGE Aircraft EnginesgThermodynamic Station Representation897Wf ExpansionA/B Temp RiseW2A8 (nozzle LP Turbine expansionComb Temp RiseFan Pr (P25/P2)HPC Pr (P25/P2)area)HP Turbine expansion15(P25/P2)Overall Pressure Ratio (P3/P2)GE Aircraft EnginesgFanCompressorBypass FlowAir FlowBypass FlowCombustorHPT LPTA fterburnerInlet Exit HP SpoolLP SpoolAugmented Turbofan Engine Cross-Section16 General Electric Aircraft EnginesGE Aircraft EnginesgDesign Considerations-Process Centering and VariationOff-TargetVariationXXXXXXD esign ConsiderationsProcess Centering and VariationXXXXXXXXXXXXXXXXXOn-TargetXXXR educe SpreadCenterProcessXXXXXXXXXXXXXXSix Sigma Methodology Applies Statistical Analyses to Center SpreadProcess17ggyppyProcesses and Minimize VariationGeneral Electric Aircraft EnginesGE Aircraft EnginesgProbabilistic Design

9 Techniques Account for Process VariationGeneral Electric Aircraft EnginesgqFrequency ,000 Trials 0 OutliersForecast: Margin-: Average Off TargetLSLT D M O T Frequency ,000 Trials 49 OutliersForecast: Margin: High VariationLSLT D M H V is from to + M Certainty is from to + M Forecast: Margin:On Target-Low VariationFrequency ,000 Trials 1 Outlier Reduce SpreadCenterProcessLSLT O T L V LSL L S L . and Accounting for Process Variation AssuresCompliance with Design Limits


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