-- NASA Technical Memorandum 83660 AIAA-84-1184 NASA-TM-83660 /_o°4oo/'76q4/
Development of Dynamic Simulation of TF34-GE-100 Turbofan Engine with Post-Stall Capability
Susan M. Krosel Lewis Research Center Cleveland, Ohio
a i : t ii
l__,12L.--'.'i. ' - _.227'.T-2 L'. :..,2 ' " ' H:, . ,...... A Prepared for the Twentieth Joint Propulsion Conference cosponsored by the AIAA, SAE, and ASME Cincinnati, Ohio, June 11-13, 1984 1 RN/NASA-TM-S3SGG
~-21G4 NAS 1.15~S366e AiHA-24-1184 11 PAGES
t !TT~ '; -+ i ,.:,::!-...-.:.:! -, ..-.. •...: 1 1 L: \.'-:, ""'"••...., I Cl I
Natio~cil A2fO~dUt!CS Clev~idnd, Ohio. --'- +~-_r-... cit \.;;-= 11-13 .Jurl. MAJS~ /*ANALOG COMPUTERS/*COMPUTERIZED SIMULATION/*ENGINE FAILURE/*TURSOFAN DIGITAL CQMPUTERS/ MATHEMAT1CAL MODELS; PERFORMANCE TESTS/ REAL OPERAT i f}f-J
------_.....------~~ AIAA-84-1184 Developmentof DynamicSimulationof TF34-GE-100TurbofanEnginewith Post-StallCapability SusanM. Krosel,NASALewisResearch Center,Cleveland,OH
AIAA/SAE/ASIVlE 20thJointPropulsionConference June 11-13,1984/Cincinnati,Ohio
Forpermissiontocopyorrepublishcontact, theAmericanInstituteofAeronauticsandAstronautics 1633Broadway,NewYork,NY10019 DEVELOPMENTOF DYNAMICSIMULATIONOF TF34-GE-100TURBOFAN ENGINEWITH POST-STALLCAPABILITY SusanM. Krosel NationalAeronauticsand SpaceAdministration LewisResearchCenter Cleveland,Ohio 44135
Abstract TB turbine f fuel This paper describes the development of a i initial condition hybrid computer simulation of a TF34-GE-IO0 turbo- in into volume fan engine with post-stall capability. The simu- out out of volume lation operates in real-time and will be used to test and evaluate stall recovery control modes for Introduction this engine. The simulation calculations are per- formed by an analog computer with a peripheral The desire for increased performance from multivariable function generation unit used for aircraft gas turbine engines has resulted in computing bivariate functions. Tabular listings engine operation close to stall. Because of this, of simulation variables are obtained by inter- the possibility of engine stall has increased. In facing to a digital computer and using a custom most instances of stall, there is a momentary software package for data collection and display, change in the engine airflow pattern and a loss in thrust. Usually, the engine returns to its normal Nomenclature _perating condition without the need for cor- rective control action. This is a recoverable A area stall. However, in some cases, the engine fails cd' nozzle flow coefficient to recover and settles at a stable, low-thrust, cfp nozzle flow parameter operating point with low rotational speeds and cv specific heat, constant volume high turbine temoeratures. To restore power and F force prevent serious engine damage, the engine must be gc gravitational conversion constant shut down and restarted. This is termed nonrecov- HVF heating value fuel erable or "hung" stall. ah enthalpy h enthalpy drop The reasons why some stalls are recoverable (hw) energy and others deqenerate into nonrecoverable stalls I rotor inertia are not fully known or understood. The NASA Lewis J mechanical equivalent of heat Research Center is conducting a research program K constant to gain a better understanding of stall occurrence length and to design and evaluate control strategies for N rotor speed stall recovery. P pressure AP pressure drop A necessary tool in the understanding of stall (PIP) pressure ratio _henomena is a mathematical model of the engine Ra gas constant of air dynamics. Such a model must accurately describe R flow resistance both the normal out-of-stall and the in-stall T temperature behavior of the engine. Previous work has been T' downstream temperature doneI to develop a post-stall model/simulation (T/T) temperature ratio of the General Electric TF34-GE-100 engine tfp turbine flow parameter compression system. That simulation is capable of thp turbine enthalpy parameter producing recoverable and nonrecoverable stalls, V volume depending on the value of certain engine para- W stored mass meters. However, that simulation is limited to operation at fixed compressor and fan speeds since Q flow the engine turbine models and rotor dynamics are 6 total pressure relative to S-L not included. specific heat ratio n efficiency To evaluate control strategies for stall B total temperature relative to STD recovery, a simulation that can represent steady- state and dynamic engine Derformance over a full Subscripts ranae of operating conditions (i.e., out-of-stall and'in-stall) is required. Furthermore, if the BLD bleed simulation is to be used to validate actual C compressor control system software and/or hardware, then the CB combustor simulationmust operate (i.e., solve the dynamic FC fan or compressor equations) in real time. Hybrid computer simu- FH fan hub lations have been shown to provide this real-time FT fan tip response while _etaininq a high deoree of steady- I inlet state accuracy._ " " N nozzle This oaper describes the formulation of a mathematical model and the development of a full
This paper is declared a work of the U.S. Copyright_ AmericanInstituteof Aeronauticsand GovernmentandthereforeisJnthepublicdomain. Astronautics,Inc.. 19M.Allrightsre_ed. range, real-time, hybrid computer simulation of TF34 engine data were needed when developing the TF34-GE-100 turbofan engine, models of specific components. Figure 2(A) shows the computational flow in the model for normal The mathematical model of the out-of-stall engine airflow. In Fig. 2(B), component models engine performance was derived from the engine that must account for reverse flow or rich fuel- manufacturer's steady-state digital simulation of air mixtures are noted. the engine. The in-stall m_d_l was based on the results of Greitzer's work._-_ Many of the as- For steady-state accuracy, wide range per- sumptions and techniques used to develop the over- formance maps are included for the fan and com- all hybrid simulation were based on earlier pressor. To provide transient capability, fluid developments of real-time hybrid computer simu- momentum, mass and energy storage and rotor lations of the Pratt and Whitney TF30-P-3 and inertias are included. Intercomponent volumes are FIOO-PW-IO0 augmented turbofan engines.6-8 assumed at engine locations where gas dynamics are considered important or necessary to avoid The engine model was programmed to run on one iterative calculations. Dynamic forms of the of the NASA Lewis Research Center's two hybrid continuity and energy equations and the state (analog and digital) computer systems. The bulk equation are solved for stored mass, temperature of the simulation calculations are performed on and pressure in each volume. The effect of fluid the analog computers. A peripheral multivariable momentum on engine dynamics is also considered in function generation unit is used to evaluate the this simulation. The momentum equation is solved model's bivariate functions. The digital computer for flow in the fan tip, the fan hub and the was interfaced through analog-to-digital con- compressor. verters (ADC's) and a custom software package was developed for data collection and display. For flow reversal which may occur during stall, the source temperatures for the affected Engine Description energy equations are switched from the normal upstream temperatures to the temperatures within The TF3_-GE-IO0 turbofan engine is designed the particular volume. To avoid discontinuities and manufactured by the Aircraft Engine Group of in the corrected speed for the fan and compressor, the General Electric Company in West Lynn, the upstream temperature value is still used as Massachusetts. The TF34-GE-IO0 is a dual rotor, the correcting temperature during reverse flow. front fan, two stream, separated flow, high bypass These in-stall models for the inlet, fan, and ratio turbofan engine. A single inlet supplies compressor are based on the work reported in Ref. airflow to a single stage fan. After leaving the I. Fan or compressor stall is detected when, for fan, this airflow separates into two streams, one a specified corrected speed, airflow is less than through the engine core; the other through the the airflow at the stall line. To attain real- bypass duct. Since the TF34 has a high bypass time response of this simulation and to minimize ratio, the bulk of the airflow passes through the the number of analog components needed, some bypass duct and when exhausted, provides the major simplification of the basic aerothermodynamic portion of engine thrust, relationships in the model was necessary. Fluid properties, such as specific heats and gas con- The core airflow passes through the com- stants, were assumed to be constant (i.e., pressor which has fourteen stages and variable independent of temperature and fuel-air ratio) stators. In the combustor, the air is mixed with over the engine operating range. Additionally, fuel and burned, providing the hot gases to drive the effect of fuel-air ratio on enthalpy in the the turbines. The gas generator turbine drives turbine volumes was assumed negligible. the compressor. It consists of two air-cooled stages and is connected to the compressor by a Descriptions of the individual component hollow shaft. The fan turbine has four stages and models follow. General forms of the equations are drives the fan through a shaft concentric to the given. gas generator shaft. Inlet The bypass duct airflow and core gas flow exhaust through separate nozzles. The exhaust The inlet is modelled as a pressure drop using nozzle areas are fixed and convergent. The core the general equation form stream convergent nozzle is concentric to the representationbypass stream convergentof the TF34-GE-100nozzle. turbofanA schematicengine _I : aPIIR (I) is given in Fig. 1. Engine station identi- The inlet conditions are set as necessary to fications are also given, attain the desired fan inlet conditions. Volume Model dynamics for mass and energy storage are in- cluded. The forms for the energy and stored mass The mathematical model of the TF34-GE-IOO equations, used in this model, are turbofan engine must represent steady-state and r dynamic engine performance over a full range of d (WT) * | * Tin) - _ (Wout * T_ (2) operating conditions (i.e., out-of-stall and in- _ : _ L_ (_in J stall). The mo_e_ reported herein differs from previous modelsu-° in that it provides for in- d stall operation. This model is based, to the _t (W) = Z_in- _Wout (3) extent possible, on data obtained from the engine manufacturer'slation._ In somesteady-statecases, otherdigitalsourcessimu-of where _.in denotes flow into the volume, _out denotes flow put of the volume, Tin is upstream Compressor temperature, and T is the temperature of the As with the fan, the out-of-stall steady-state volume. The inlet pressure and temperature are performance of the compressor is represented by an calculated from the gas state equation overall performance map. Inputs to this bivariate P * V = W * Ra * T (4) map are corrected compressor flow and corrected compressor speed. The output of the map is the During flow reversal in stall, the inlet acts compressor pressure ratio, (P/P)c. Compressor as an energy sink. As discussed earlier, the temperature ratio, (T/T)c, is fit as a function reference temperatures change and hence, the form of the pressure ratio. Volume dynamics for the of the energy equation becomes energy and stored mass, (WT)C and WC, are included. These are similar in form to Eqs. d (WT) = _ * (E (Win * T) - E (Wout * T')) (5) (2) and (3) of the Inlet. Compressor flow, ¢_, is calculated by a momentum equation similar to Eq. (6) given in the Fan. where T' is the downstream temperature. AS for the fan, the in-stall model is based on Fan the compressor model contained in Ref. I. The stalled form for the compressor energy equation Overall performance maps are used to represent reflects the changes in reference temperatures as the out-of-state steady-state performance of the shown in EQ. (5) for the Inlet. A phi-psi re- fan. There are separate maps for the fan tip and lationship from Ref. 1 calculates the stalled hub sections due to the radial pressures gradient pressure and temperature for both reversed and that exist in the fan. The fan tip and fan hub forward compressor flow during stall. pressure ratios, (P/P)FT and (P/P)FH, are computed from bivariate functions of corrected Bleeds total fan airflow and corrected fan speed. Cor- responding fan discharge temperature ratios, Compressor discharge bleed is used for turbine (T/T)FT and (T/T)FH, are calculated as line- cooling. The turbine in-flow bleeds are modelled ar functions of the respective pressure ratios, simply as constant proportions of compressor This avoids having to compute fan adiabatic flow. The general equation form is efficiency and calculations involving expo- nentiation. From the fan tip and fan hub pressure and temperature ratios, the fan tip and fan hub _BLD = KBLD * _C (7) pressures and temperatures, PFT, PFH, TFT, and TFH are calculated. Volume dynamics for Combustor the fan tip and hub volumes are included. The equations for the energy and stored mass, Combustor airflow is calculated directly from (WT)FT, WFT, (WT)FH, and WFH are similar the pressure drop across the combustor given by in form to Eqs. (2) and (3) of the inlet. Energy contributed by shaft work is accounted for by the calculation of the fan discharge temperatures. * (8) Fan duct and compressor inlet pressure and temper- _CB =_/PcB (aP)cB/(KcB * TCB) ature conditions are calculated from the gas state Eqo (4). Radial crossflow in the engine goose- An algebraic energy equation replaces the neck, between the fan tip and hub sections is dynamic form and is used to calculate combustor assumed to be proportional to the pressure dif- enthalpy such that ference. Zero crossflow is assumed at the design steady-state point. Additionally, flow dynamics hCB = (hW)cBl_CB,out (9 are considered for the fan tip and fan where hub flows, _FT and @FH by use of fluid momentum equations. The general form for the momentum (h_)cB =hcB, in * _CB,out + _f * (n * HVF) (10 equation is t The combustor temperature is computed from a = (I/_) _o (a (P * A) + F) dt + _i (6) bivariateratio. Thisfunctionfunctionof enthalpyis based andon datafuel-aircontained in the standard gas tables.10 Since no mixing The in-stall fan model is based on the model of the flows occurs in the combustor discharge of Ref. i. The stalled energy equations for the volume, a simple first order lag is used in place fan tip and fan hub volumes provide for changes in of the dynamic energy equation. The time constant the reference temperatures as was done for the is assumed to be equal to the ratio of the stored Inlet volume. The form of these energy equations mass in the volume to the flow through the is similar to Eq. (5) of the Inlet. volume. Combustor pressure is calculated from the gas state Eq. (4). The stalled pressures and temperatures of the fan are calculated from the phi-psi relationship In stall operation, the fuel-air mixture in given in Ref. I. This simplifies the fan stall the combustor becomes rich. This is due to the model by avoiding bivariate map evaluations during decrease in airflow from the compressor. Unburnt stall. Reversed and forward fan flow during stall fuel remains after combustion. This causes a is accounted for in these equations, decrease in combustor efficiency. The stall combustor model computes degraded combustor efficiency as a function of fuel-air ratio. TurbinesThe turbinemodelsdiffersignificantlyfrom cfPN = * * [
_TB = (tfp)* _TB)/_/'6_B (11) QTB = (60* J/2 * _) * (ahTB* _TB)/N (17)
AhTB = (thp* OTB) (12) QFC= (60 * Of2 * _) * ((hout - hin)FC re-enterCoolingthebleedflow forstreameachatturbinethe dischargeis assumedof theto * _Fc)/N (18) turbine. The coolingbleedsdo not performany turbine work. The form of the energyequationfor Implementation the turbinesrequiresthe calculationof enthalpies.As previouslymentioned,the The enginemodelwas programmedto run on one enthalpiesare calculatedas functionsof tempera- of the NASA LewisResearchCenter'stwo hybrid ture,neglectingthe effectof fuel-airratio, computersystems(fig.3). Each systemconsists The form of the energyequationfor the turbine of an ElectronicAssociatesInc. (EAI)PACER600 volumesis hybridcomputerand assortedperipherals.Each hybridcomputerconsistsof one PACER100 digital
d _ ]WT)TB = -I [_-_(_TB,iR,hTB,in) computer,and a modeltwo693modelhybrid681 (orinterface.680) analogA multi-consoles, CVTB variablefunctiongeneration(MVFG)unit is availableas a peripheralto the analogcomputers.
1 hTB *_-]_TB,ou_ (13) The TF34-GE-IOOturbofanenginesimulation uses two model681 analogconsoles,one model680 Turbinepressureand temperatureare analogconsole,and the MVFG unit. The consoles calculatedfrom the gas stateEq. (4). and the MVFG unit are connectedto each other throughthe CentralTrunking System. Figure4 Duringstall,unburnedfuel may enterthe showsthe computationalbreakdownamongthe three turbineswith the possibiltiyfor combustion, consoles. Some univariatefunctionsare imple- Dependingon wherethe combustiontakesplaceand mentedusingdigitallycontrolledfunctiongener- on how the heat releaseaffectsthe turbinework ators,DCFG'sthat are availableon the analog output,considerablemodelvariationis possible, consoles. Resultsfrom variouseffortsto modelthis combustionprocesshave not indicatedthatthe To attainthe real-timeresponseof the simu- processsignificantlyaffectssimulationresults, lation,the MVFG unit is used for bivariate Becauseof the complexityof a turbinecombustion functiongeneration.Use of the digitalcomputer model and the real-timeconstraintof this simu- for evaluationof bivariatefunctionsrequireda lation,the turbinecombustionprocesswas not time-scalingof the analogby a factorof 100. includedin this model. The digitalcomputerintroduceda delaythat preventedstable,real-timeoperationof the Nozzles simulation.Becauseof the use of the MVFG's,the digitalcomputeris not necessaryfor the simu- Basedon availabledata,pressurelossesin lationcalculations.It is used for set up and the bypass and the core ducts were assumed to be check out of the analog consoles and MVFG unit small. Thesepressurelosseswere lumpedinto the priorto simulationoperation. core and bypassnozzles. The nozzleflow co- efficientswere adjustedto providethe correct The digitalcomputeris also used to obtain nozzleflowsfor the givenpressureratios. The listingsof steady-statesimulationdata. A NASA generalequationform used to calculateflow for developedsoftwareexecutiveEXECIand an inter- the bypassand core nozzlesis active.dat_collectionand displayprogram INFORMIZ,13 are used in the simulation. l _N = (CdN" AN • cfPN * PN)I_'N.., (14) Selecteddigitalcomputerenginevariablesvia analog-to-digitalare read intoconverters,the and are processedby INFORM. Guidelinesfor use of the EXECIand INFORMsoftwareare givenin Ref. The adjustednozzleflow coefficient,Cd'N, 13. is fit as a functionof nozzlepressureratio. The nozzleflow parameter,cfPN, is calculatedfrom
4 Concludin9 Remarks 4. Greitzer,E. M., "Surgeand RotatingStallin AxialFlow Compressors,I: TheoreticalCompressor A full-range,real-timehybridsimulationof SystemModel,"ASME Paper75-GT-9,Mar. 1975. the TF34-GE-IO0turbofanenginewith post-stall capabilityis currentlybeingdeveloped.The 5. Greitzer,E. M., "Surgeand RotatingStallin enginemodelequationsare basedon data obtained AxialFlow Compressors,II. ExperimentalResults from the enginemanfacturer'ssteady-statedigital and Comparisonwith Theory,"ASME Paper75-GT-10, simulationof this engine. Dynamicformsof the Mar. 1975. continuity,energy,and momentumequationshave been addedto providethe requiredtransient 6. Szuch,J. R., and Bruton,W. M., "Real-Time capability.Wherenecessary,simplificationsto Simulationof the TF30-P-3TurbofanEngineUsinga the basicequationshave beenmade to attainreal- HybridComputer,"NASATM X-3106,1974. time responseof the simulation.As of the writingof this paper,the out-of-stallsimulation 7. Szuch,J. R., and Seldner,K., "Real-Time is runningin real-timeon the hybridcomputer. Simulationof FIOO-PW-IO0TurbofanEngineUsing The in-stallcharacteristicsfor the fan and the HybridComputer,"NASATM X-3261,1975. compressorhave been incorporatedintothe simu- lationand are beingcheckedout. Once the simu- 8. Szuch,J. R., Seldner,K. and Cwynar,D. S., lationis fullyoperational,it will be validated "Developmentand Verificationof Real-TimeHybrid by experimentaldata from enginestallteststhat ComputerSimulationof FIOO-PW-IO0(3)Turbofan are planned. Eventuallythis simulationwill be Engine,"NASATP-I034,1977. used to test and evaluatevariousstallrecovery controlschemesthat are now underdevelopment. 9. "InstructionManualfor ComputerProgram TF34/74018/,"GeneralElectricCompanySAO Memo References 74SC18,Aug. 31, 1974.
I. Wenzel,L. M., and Bruton,W. M., "Analytical 10. Keenan,J. H., and Kaye,J. A., Gas Tables. Investigationof NonrecoverableStall,"NASA John Wiley,New York,1948. TM-82792,1982. 11. Glassman,A. J., "TurbineDesignand 2. Szuch,J. R., Soeder,J. F., Seldner,K., and Application,"vol I, NASA SP-290,1972 Cwynar,D. S., "F100MultivariableControl " " SynthesisProgram: Evaluationof a Multivariable 12. Cwynar,D. S., "INFORM: An InteractiveData ControlUsing a Real-TimeEngineSimulation,"NASA Collectionand DisplayProgramWith Debugging TP-1056,1977. Capability,"NASATP-1424,1980. 3. Day, I. J., Greitzer,E. M., and Cumpsty,N. 13. Bruton,W. M., and Cwynar,D. S., "Lewis A., "Predictionof CompressorPerformancein HybridComputingSystem,UsersManual,"NASA RotatingStall,"Journalof Engineerin_ for Power, TM-79111,1979. vol. 100, no. i, Jan. 1978,pp. 1-14. HIGH PRESSURE COMBUSTOR? TURBINE7 COMPRESSOR /' /// / " I. .\ Hi'l ,, 13 2 Figure 1. - TF34-GE-IOO turbofan engine schematic. FAN BYPASS TIP NOZZLE INLET FAN _ COMPRESSOR _ COMBUSTOR PRESSURE PRESSURE CORE HUB TURBINE TURBINE NOZZLE (a)Normalengineairflow. FAN BYPASS TIP NOZZLE INLET PRESSURE PRESSURE CORE TURBINE NOZZLE HuBFAN_ COMPRESSOR _ COMBUSTOR -_,T.URBINE STALLEDFLOW(REVERSEDIFOR'V_/ARD) RICHFUELIAIRVMIXTURES (b)Stalledengineairflow. Figure2. - Flowdiagram. Figure3. - NASALewisResearchCenterhybrid computerfacility. 681ANALOGCONSOLE 681ANALOGCONSOLE 680ANALOGCONSOLE • COMBUSTORMODEL • INLETMODEL •FANVOLUMEDYNAMICS • HIGHPRESSURETURBINEMODEL • FANSTEADYSTATEPERFORMANCE •COMPRESSORMODEL • LOWPRESSURETURBINEMODEL • FANSTALLEDPERFORMANCE •HIGHSPEEDROTORDYNAMICS • LOWSPEEDROTORDYNAMICS • COMPRESSORSTALLEDPERFORMANCE • DCFGFUNCTIONS • STALLDETECTIONLOGIC J'l CENTRALTRUNKINGUNITI= l HYBRID DIGITALCOMPUTER MVFGUNIT INTERFACE -ANALOGANDMVFGSETUP l _i"FAN,COMPRESSOR,AND • ADC'S • DATACOLLECTIONANDDISPLAY I COMBUSTOBIVARIATER H I I"FUNCTIONS Figure4. - Computationalbreakdownofsimulation. 1. Report No. NASATM-83660 2. Government Accession No. 3. Recipient's Catalog No. AIAA-84-1184 " 4. Title and Subtitle 5. Report Date Development of Dynamic Simulation of TF34-GE-100 Turbofan Engine with Post-Stal I Capabi I i ty e PertormlngOrganizaticon_e 505-40-5B 7. Author(s) 8. Performing Organization Report No. E-2104 Susan M. Krosel 10. Work Unit No. 9. Performing Organization Name and Address 11.ContractorGrantNo. National Aeronautics and Space Administration Lewis Research Center C1evel and, Ohio 44135 13.Typeof Reportand PeriodCovered _12.Sponsoring Agency Name and Address Techni cal Memorandum National Aeronautics and Space Admini stration 14Sponsoring Agency Code Washington, D.C. 20546 15, Supplementa_ Notes _reoared for the Twentieth Joint Propulsion Conference cosponsored by the AIAA, SA_, and ASME, Cincinnati, Ohio, June 11-13, 1984. 16. Abstract This paper describes the development of a hybrid computer simulation of a TF34-GE-100 turbofan engine with post-stall capability. The simulation operates in real-time and will be used to test and evaluate stall recovery control modes for this engine. The simulation calculations are performed by an analog computer with a peripheral multivariable function generation unit used for computing bivariate functions. Tabular listings of simulation variables are obtained by interfacing to a digital computer and using a custom software package for data collection and display. 17. Key Words (Suggested by Author(s)) 18. Distribution Statement Propulsion systems; Engine simulation; Unclassified - unlimited Stall recovery STARCategory 07 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of pages 22. Price" Unclassi fled Unclassified "For sale by the National Technical Information Service, Springfield,Virginia 22161