I_B/ 5i_- 7_ -g$su I

NASA Technical Memorandum 83561 NASA-TM-83561 19840008116

!

I HYTESS._A Hypothetical Turbofan

Engine Simplified Simulation

Walter C. Merrill

Lewis Research Center

Cleveland, Ohio

and

Edward C. Beattie and Richard F. LaPrad

Pratt & Whitney Aircraft Co.

United Technologies Corp.

East Hartford, Connecticut

and

Stephen M. Rock and Muhammed M. Akhter

Systems Control Technology, lnc.

Palo Alto, California

......_ - I.+._'!

, January 1984 ___:_-;,,,I .,a,._A _; ,._.,

H...... _,_,._,wl;_Gl,_r_ " ,, . .,-

HYTESS- A HYPOTHETICALTURBOFANENGINESIMPLIFIED SIMULATION

Walter C. Merrill

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135

Edward C. Beattie and Richard F. LaPrad

Pratt & Whitney Aircraft Co.

United Technologies Corp.

East Hartford, Connecticut 06108

and

o Stephen M. Rock and MuhammadM. Akhter

Systems Control Technology, Inc

l Palo Alto, California 94303

SUMMARY

A hypothetical turbofan engine simplified simulation is presented. The

digital program, written in FORTRAN,is self-contained, efficient, realistic,

and easily used. This simulation was developed from linearized operating point

models but still retains essential nonlinear engine effects. The simulation

is representative of a hypothetical, low bypass ratio turbofan engine. Program

structure and input and output information are provided. This simulation can

be used for engine dynamics and controls analysis.

INTRODUCTION

This report is a users manual for the hypothetical turbofan engine simplified simulation (HYTESS). This digital simulation exists as FORTRANsource

code and was designed for use on the NASALewis Research Center's IBM 3033 AP

computer running under the TSS/370 operating system. The program is selfcontained and was developed to offer those interested in engine dynamics and

controls research an efficient, realistic, and easily used engine simulation.

Typically turbine engine simulations incorporate detailed nonlinear descriptions of both steady-state and dynamic engine operation throughout the

engine's flight envelope. These detailed nonlinear simulations are very accurate and realistic and, when implemented in a digital computer, require relatively large amounts of computer storage and computer processing time. This

makes these detailed simulations difficult and costly to use. HYTESSwas developed as an alternative. It is structurally simpler than a full nonlinear

engine simulation and therefore has reduced storage and processing requirements. HYTESSretains the essential nonlinear effects inherent in the engine's

operation. This is accomplished by modeling the engine using a linear state

space formulation, and incorporating the nonlinear characteristics by representing the matrix elements within the linear state space structure as nonlinear functions of various engine variables. The compromise implied in this

process is that, although the fidelity of HYTESSis maintained for the variables considered, it is very difficult to identify individual component behavior
as in a detailed simulation. Also HYTESSis restricted to operation in regions

about the normal operating line of the engine. The engine characteristics simulated by HYTESS,although hypothetical, are qualitatively similar to those of

realistic advanced turbofan engines. Typical applications for this simulation

would include open-loop engine dynamics studies as well as closed-loop controls

analysis using a user generated control law.

This report begins with a description of the engine simulated by HYTESS.

Next descriptions of the mathematical model and the simulation are given. Finally, some results are given. Flow charts and variable definitions are also

included.

ENGINEDESCRIPTION

The engine simulated by HYTESSis representative of current high technology engines and is shown schematically in figure I. It is a low bypass ratio,

twin-spool, axial-flow turbofan engine, consisting of the following components:

(I) Low-speed fan driven by a turbine (spool I)

(2) High-speed compressor driven by a turbine (spool 2)

(3) Main burner

(4) Annular fan duct that surrounds the basic gas generator and discharges

air into the mixed flow augmentor

(5) Variable area nozzle

Variable inlet guide vanes are used ahead of the fan to improve inlet distortion tolerance and fan efficiency. Variable stators in the high compressor

improve starting and high Mach number characteristics. Airflow bleed is extracted at the compressor exit to improve starting. The exhaust nozzle variable geometry enables all three nozzle performance parameters (nozzle area, expansion ratio, and boattail drag) to be simultaneously near optimum throughout

the operating range. A list of engine inputs and outputs is given in the next

section.

Engine Model

A detailed nonlinear engine model can be written in vector differential

equation form

• I

X : f(X,U,¢)

' (1)

Y : g(X,U,_)

where X is a state vector, U is the vector of controls, Y is the output

vector, and @ is a vector of environmental conditions. Detailed nonlinear

engine relations are represented by the functions f(-) and g(o). At a base

point, that is a steady-state point on the operating line,
]

f(Xb,Ub,¢b) = 0 [, (2)

Yb = g(Xb'Ub) J

In HYTESS the state space descriptionof the model of equations(1) and (2) is

implementedas

Xss = Xb - F-IG(u _ Ub)

X : F(X - Xss) (3)

Y = Yb + H(X - Xb) + D(U - Ub)

The subscript b is used to denote base points. The subscript ss is used to

denote the steady-state value of X for a given U. The matrices F, F-IG, H,

and D are the typical system matrices. The states, control inputs, and outputs were chosen to be typical of those variables used in dynamics and controls

analysis in modern turbofan engines and consist of the following variables.

States:

X1 fan speed (NI), rpm

X2 compressor speed (N2), rpm

X3 burner exit slow response temperature (TT4PLO), K

X4 fan turbine inlet slow response temperature (TT45LO), K

Control inputs:

Ul main burner fuel flow (WFMB),kg/sec

U2 nozzle jet area (AJ),mz

U3 fan guide vane position (FGV),deg

U4 high compressorvariablestator vane angle (SVA),deg

U5 customercompressorbleed flow (BLC),percent

Engine outputs:

Yl fan speed (Nl), rpm

Y2 compressorspeed (N2),rpm

Y3 burner pressure (PT4),N/m2

Y4 augmentorpressure (PT6),N/m2

Y5 fan turbine inlet temperature(FTIT),K

Y6 thrust (FNMX),N

Y7 compressorsurgemargin (SMHC)

Operatingconditions:

_l engine face pressure (PT2),N/m2

_2 engine face temperature(TT2),K

The systemmatriceswere determinedin the followingmanner. Linearizedsystem matrices at several base pointswere found from a representativedetailed

nonlinearsimulationusing perturbationaltechniques• The elementsof each of

these matriceswere regressedupon selectedenginevariablesor elementary
functionsof these variables(elementsof Y and _). As a resultnonlinear

polynomialfunctionswere found that fit the change in these matrix elements

for the full range of engine power through the flight envelopeas shown in

figure 2. An example of some typical regressionpolynomialsfor the system

matrices is given in table I. Rewritingequation (3) with a more explicit

functionalnotationyields

Xss = Xb(Y,_ ) - [F-IG](y,_)[U - Ub(Y,_)]

I

X : F(Y,_)[X- Xss] I (4)

Y = Yb(Y,_) + H(Y,_)[X- Xb(Y,_)]+ D(Y,_)[U- Ub(Y,_)] J

EngineControl Model

The purpose of an engine control is to manipulatethrust accordingto the

pilot's request. In this simulationthe control is simplyan open-loopschedule between the pilot'srequest (PLA) as the independentvariableand the requested enginecontrolsas the dependentvariables.

, ! Ur: h(PLA,_) (5)

The function h(_) is selectedto definethe desired steady-staterelations

between PLA and the engineoutputs. These steady-staterelationsare often

called referencepoint schedulesand are simulatedin the subroutineRPSCH.

The open-loopcontrol law then becomes

u = ur (6)

Closed-loop control could be incorporated in the simulation by appropriately

modifying the implementation of equation (6) in the subroutine TRANS. For

example, immediately following the call to subroutine RPSCHin TRANS, equation

(6) is implemented. Closed-loop control could be implemented here simply by

including the closed-loop component UCL as in equation (7).

u = uR + UCL (7)

SIMULATIONDESCRIPTION

This sectioncontainsa descriptionof the program,input programrequirements, output, and executionrequirements• Selectedtest case results are also

presented•

4
Program Description

HYTESScontains all the subroutines necessary to execute the program.

There are no system library routines required. The program was originally developed for execution on a VAX 11-780 but has since been executed on an IBM

3033AP with no changes. The program is written in FORTRANIV, and it is anticipated that few modifications will be required to execute the program on any

system of adequate size that supports FORTRANIV. The program itself consists

of a main program and 27 subroutines and 3 block data routines. (See table II

for program hierarchy.) There are a total of seven levels with a maximumof

six levels of nested subroutines. For example at level II the subroutine INLET

(called by MAIN) calls four subroutines: ALTABL, PRCMB,HFTA, and TFHA. Subsequently, PRCMB,HFTA, and TFHAall call PVAL. Subroutines are listed in the

order of their first occurrence in the calling program. Several of the subroutines may be called more than once by the calling routine. No attempt has

been made to show multiple calls in table II. In table III a description of

the purpose of each subroutine and block data is given.

Basic program flow is shown in figure 3. Essentially, the program initializes, reads input data, calculates a steady-state point, and if required,

calculates a user-specified transient. The program accepts as steady state or

transient input either of the following two sets of inputs:

Input set 1 (IS1)

Altitude (Alt)

Mach number (MN)

Power level angle (PLA)

Input set 2 (IS2)

Altitude (Aft)

Mach number (MN)

Fuel flow (WFMB)

Nozzle area (AJ)

Fan guide vane angle (FGV)

High compressor stator vane angles (SVA)

Bleed flow (BLC)

Input set 1 would typically be used to simulate open-loop engine response to

pilot PLA requests. Input set 2 would be more useful for controls analysis.

The program also accepts, as input, program control parameters which define

and control steady-state and transient execution of the program. Figure 4 describes the iteration performed to establish a steady-state point. Note that

all iterations require the evaluation of both the base point quantities and the

system matrices as described in equation (2). The procedures for calculations

depend on the particular input set chosen. If ISl is used the base points are

found from the reference point schedules (RPSCH)directly using the specified

PLA. IF IS2 is used a "virtual" PLA is first found which corresponds to the

specified rotor speed. This virtual PLA is then used by the reference point

schedules to determine the base points (note that this is also the procedure

used during transient simulation). In both cases tne system matrices are determined from the base point values and the engine face conditions.

The model equations then are used to generate estimates of X and Y.

The low rotor speed estimate (NI predicted) obtained from the model equations
is then used to begin the steady-statecalculationprocess anew. This iteration on low rotor speed continuesuntil convergenceis achievedand a steadystate conditionis found.

The program will simulateengine transientoperationfor time history inputs of PLA or control inputs (WFMB,AJ, FGV, SVA, BLC). Initialconditions

for a simulatedtransientare the steady-statevalues obtainedusing the procedure of figure4. Transientprogram operationas shown in figure 5 is very

similarto the steady-statecase. The significantdifferenceis that the iteration through the basic loop is not terminatedby a convergenceprocess.

Each iterationrepresentsan updateof the Euler integrationscheme and the

iterationcontinuesuntil the specifiedfinal time is reached. AppendixA is

a descriptionof importantsimulationparameters.

InputRequirements

HYTESS uses the FORTRAN input mode called Namelistto accept valuesfor

input parameters. There are three namelistsused in subroutineREADIN to define input parametersINPUT,INTRAN,and PLOT. Two examplesof program input

which correspondto ISl and IS2 are given in tables IV and V, respectively.

Namelist INPUT

The namelist INPUT is used to define the steady-state input. All of the

variables used to define a steady-state engine condition as well as some option control parameters are contained in namelist INPUT. The variable names,

their default values, and descriptions are given in table VI. For example in

table IV the namelist INPUT is used to (I) indicate that a transient is required (TRAN= I); (2) indicate that plotting variables are to be saved

(IPLOT = I); and (3) define the initial conditions for IS1 (SALT = 0.0,

SMACH= 0.0, SPLA = 20).

Namelist INTRAN

The namelist INTRANis used to define the input necessary for an engine

transient. This namelist is only read if TRAN: 1.0 in the namelist INPUT.

All of the parameters entered via this namelist are entered in the following

array format

ARRAY : tl,vl,t2,v 2, . .., tn,V n

where ARRAYrepresents the respective variable array and tl,v I is a time/

value pair. Up to seven pairs may be entered for each array variable, i.e.,

n < 7. The INTRANnamelist parameters are accepted as either step or ramp inputs. Since the particular array variable is specified at n discrete time

points, the intervals between time points need to be further specified. This

is accomplished by defining step and ramp inputs. For a step input the array

value in any interval, say t i to ti+l, is equal to the preceding time point

array value v i. For a ramp input, the array value in any interval lies on a

straight line defined by the two points ti,v i and ti+i,Vi+l. Variable names,
default values, and descriptions for the transient input namelist INTRANare

given in table VII. For example in table IV namelist INTRANis used to define

the print interval and the user-specified PLA transient. In this case the PLA

input is specified as shown in figure 6.

Namelist PLOT

The namelist PLOTis used to specify plotted variables. This namelist

will only be read if IPLOT = 1 in the namelist INPUT. Namelist PLOTcontains

an array variable called IPVARI which is dimensioned to 30 and therefore can

be used to specify up to 30 variables to be plotted. A certain variable is

specified for plotting by including its associated integer value (channel number) as defined in appendix A in the variable IPVARI. For example if 13, 18,

and 19 were entered into IPVARI, then fuel flow (WFMB), fan speed (SNFAN), and

compressor speed (SNCOM)would be specified for plotting.

Program Output

Figure 7 demonstrates a sample of the printout for the test case of

table IV. The program first prints the number of iterations required to reach

a steady-state point. Next the values of the states, controls, and outputs are

printed for the converged steady-state point. This output is controlled by the

subroutine STDST8. The main program output is generated by calls to the subroutine PRINT. For both steady-state and transient data subroutine PRINT

prints the variables from the commonENGOUT(appendix A) and the variables from

commonMVCOUT(appendix B). The ENGOUTvariables are labeled 'ENGINE RESPONSE _

VARIABLES' and the MVCOUTvariables are labeled 'REFERENCEPOINT SCHEDULES.'

The routine PRINT uses a lO-column format. Each column corresponds to a time

at which routine PRINT was called. The program also creates an unformatted

binary data file written on unit I0 for plotting.

Execution Requirements

HYTESSconsists of 1 main program, 3 block data routines, and 27 subroutines. Totally these 31 routines are described by 1952 lines of FORTRANIV

source code including comment statements. The approximate storage requirements

for the object modules of HYTESSon the Lewis IBM 370/3033 system are summarized in table VIII. Individual storage requirements for the commonblocks in

the three block data routines are also given in table IX. A detailed nonlinear

simulation would require approximately three times as much storage for a comparable engine.

As an indication of the execution time required by HYTESSa timing study

was accomplished for the IS1 test Case of table IV. Results of the timing

study are given in table X. These results show that a lO-sec simulated transient required 3.5 sec of CPUtime for computation. These results were calculated with a O.02-sec integration step size. Individual statistics were compiled for 13 of the more important subroutines. Time spent in those subroutines and functions not in this list is accumulated into the totals of the

nearest (in terms of hierarchy) calling subroutine in the list. The same
transient simulated on a detailed nonlinear simulation of a comparable engine

would take about 20 sec of CPUtime.

CONCLUDINGREMARKS

A hypothetical turbofan engine simplified simulation is presented. The

program is suitable for dynamics and control analysis. The simulation is

structurally simpler than a detailed performance digital simulation. However,

it does retain the essential nonlinearities of the engine and accurately simulates qualitative engine operation. The engine is modeled using a state space

structure. Elements within the state matrices are defined by polynomials whose

independent variables are functions of engine environment and engine operation.

Storage and execution time requirements are significantly less than a detailed

nonlinear simulation and are quite reasonable for typical dynamics and control

analysis studies.
APPENDIXA

SIMULATIONPARAMETERSDEFINEDIN ENGOUT

The following is the list of parameters used in the simulation. These

parameters are all defined in the COMMONcalled ENGOUTand are also printed as

the hard copy output of the program.

Channel Variable Units Description

number

1 T sec Time

2 ALT m Altitude

3 SMN --- Mach number

4 PLA deg_ Power level angle

5 PO N/m_ Ambient pressure

6 TO K Ambient temperature

7 DPO N/m2 Adder to ambient pressure

8 DTO K Adder to ambient temperature

9 PT2 psia Engine face pressure

I0 TT2 K Engine face temperature

II VO --- Airspeed at the inlet

12 ETARAM --- Ramefficiency

13 WFMBH k_/sec Fuel flow 14 AJCD m_ Nozzle area

15 FGVPOS deg Fan guide vane angle

16 SVAPOS deg High compressor stator angle

17 BLC percent Bleed flow

18 SNFAN rpm Fan physical speed

19 SNCOM rpm Compressor physical speed

20 TT4PLO K Burner exit slow response temperature

21 TT45PLO K Fan turbine inlet slow response temperature

22 SNFM rpm Fan physical speed

23 SNCM rpmo Compressor physical speed

24 PT4 N/mL Burner pressure

25 PT6 N/m2 Augmentor pressure

26 TT45 K Fan turbine inlet

27 FNMX N Thrust

28 SMHC --- Compressor surge margin

29 XTRAI --- Extra dummyvariable

30 XTRA2 --- • Extra dummyvariable

o°
APPENDIXB

SIMULATIONPARAMETERDEFINEDIN MVCOUT

The following is a list of parameters used in the simulation. These parameters are defined in the COMMONcalled MVCOUTand are also printed as the

hard copy output of the program.

Position Variable Units Description Printed

number name

1 PLAEST deg Estimated PLA N

2 TT2EST K Estimated TT2 N

3 PT2EST N/m2 Estimated PT2 N

4 SMNEST --- Mach number N

5 Not used

6 SNFEST --- Normalized estimated fan speed N

7 SNCEST --- Normalized estimated compressor N

speed

8 T25EST K Estimated TT25 N

9-20 Not Used

21 PLASS deg Reference point PLA Y

22 TT2SS K Reference point TT2 Y

23 PT2SS N/m2 Reference point PT2 Y

24 SMNSS --- Mach number Y

25 PMDSS Not used

26 SNFSCH --- Normalized reference point fan Y

speed

27 SNCSCH --- Normalized reference point com- Y

pressor speed

28 T25SCH K Reference point TT25 Y

29 FTISCH --- Normalized reference point FTIT Y

30 PT4SCH --- Normalized reference polnt PT4 Y

31 PT6MSH --- Normalized reference point PT6 Y

32 TT4PLO --- Normalized reference point TT45LO Y

33 TT45LO --- Normalized reference point TT45LO Y

34 FNMXSH --- Normalized reference polnt thurst Y

35 SMHCSH --- Normalized reference point stall Y

margin

36 WFMBSH k_/sec Reference point fuel flow Y

37 AJSCH m_ Reference point area Y

38 FGVVSH deg Reference point FGV Y

39 SVAVSH deg Reference point SVA Y

40 BLSCH percent Reference point bleed Y

I0
TABLE I. - TYPICAL REGRESSIONPOLYNOMIALSFORTHE ELEMENTS

OFTHESYSTEMMATRICES

System Element Polynomial a

matrix

0.0968 0.0019 PT62

F (I,I) - 2.463 2

6

F-IG (4,1) 0.000933 PT6 _ 0.97xi0 -9 N1 PT62

a _f_ . a2 0.03606

H (5,3) O.0311e + 0 5486xi0 -4 TT45 0.3612 " 0

D (5,1) -0.035_ + 31.3_ + 0.04914 PT4

aa = PI/14.696; e = TI/518.67.

II
TABLE II. - HYTESSPROGRAM/SUBROUTINE HIRACHY

Level

I II III IV V VI VII

MAIN SETUP

READIN

INLET ALTABL

PRCMB PVAL

HFTA PVAL

TFHA PVAL

STDST8 SNFMAP UNBAR

SNISCH SCURVE UNBAR

N2TABL SCURVE UNBAR

RPSCH N2TABL SCURVE UNBAR

SCURVE UNBAR

SPRINT

GVICAL

EMODEL SNFMPH UNBAR

RPSCH N2TABL SCURVE UNBAR

SCURVE UNBAR

SPRINT

GVICAL

FILTER ADD

SUB

MUL

SCA

PRINT SCALLA

TRANS PRINT SCALLA

NUTIME

INLET ALTABL

PRCMB PVAL

HFTA PVAL

TFHA PVAL

RPSCH N2TABL SCURVE UNBAR

SCURVE UNBAR

SPRINT

GVICAL

EMODEL SNFMAP UNBAR

RPSCH N2TABL SCURVE UNBAR

SCURVE UNBAR

SPRINT

GVICAL

FILTER ADD

SUB

MUL

SCA

ACTCRVa

ENGPRNa

MVCPRNa

aBlock data.

12
TABLEIII. - SUBROUTINEDESCRIPTION

Subroutine name Purpose

ADD General matrix addition

ALTABL Calculates temperature and pressure corrections at various

altitudes

EMODEL Calculates appropriate engine model matrices and base

points

FILTER Updates state space model equations using Euler integration

GVICAL Calculates fan guide vane (FGV) position

HFTA Calculates enthalpy as a function of temperature

INLET Solves for engine's inlet conditions

MAIN Main program for execution of simulation

MUL General matrix multiply

NUTIME Finds print interval and values of ramp functions

N2TABL Calculates N2 as a function of PLA and TT2 or PLA as a

function of N2 and TT2

PRCMB Calculates specific heat as a function of temperature

PRINT Formats and prints output of simulation

PVAL Function that evaluates a given polynomial

READIN Reads input data

RPSCH Calculates steady-state operating points

SCA Multiplies elements of a matrix by a constant

SCALLA Converts normalized variables to engineering units

SCURVE Contains data (curves) for steady-state operating points

SETUP Initializes program's namedcommons

SNISCH Finds N1 as a function of TT2, SMN, and PLA

SNFMAP Finds PLA as a function of NI, TT2, and SMN

SPRINT Table lookup routine

STDST8 Calculates a steady-state point

SUB General matrix subtraction

TFHA Calculates temperature as function of enthalpy

TRANS Controls transient execution of program

UNBAR A table lookup routine

Block data Purpose

ACTCRV High compressor stator name and nozzle area data

ENGPRN Namesfor engine inputs, outputs, and states

MVCPRN Initial values for all commonblocks

13
TABLEIV. - ISl EXAMPLEINPUT TEST CASE

&I NPUT

TRAN=I., IPLOT=I,SALT=O.,SMACH=O.,

SPLA=20.,

&END

&INTRAN

PNTBLK=O.,O.I,IO.,.I,

PLABLK=O.,20.,O.I,20.,.5,83.,IO.,83. ,

&END

&PLOT

I PVARI=I,4,22,23,24,25,26,27,28,

&END

TABLEV. - IS2 EXAMPLEINPUT TEST CASE

&INPUT

SMACH=O.,SALT=O.,SPLA=52.,TRAN=I.,

SFGVV=-25.,SSVAV=6.0,

&END

&INTRAN

PNTBLK=O.,.I,IO.,.I,

FGVBLK=O.O,-25.0,O.I,-25.0,.2,-22.5,10.,-22.5,

SVABLK=O.O,6.0,5.0,6.0,5.1,5.4,10.,5.4,

&END

14
TABLEVI. - DESCRIPTIONOF STEADY-STATENAMELISTINPUT

Variable name Default Description

TRAN 0 If TRAN=I then transient run desired

IPLOT 0 If IPLOT=I then plotting desired

SALT -999 Altitude, m

SMACH Mach number

SPLA Power level angle, deg

STAM Ambient temperature,

SPAM Ambient pressure, N/mL

SDTAM Adder to ambient temperatuare,_K

SDPAM Adder to ambient pressure, N/m_

SPT2 Engine face total pressure, N/m2

STT2 Engine face total temperature, K

SWF Fuel flow, kg/sec

SAJ Nozzle jet area, m2

SFGVV Fan guide vane angle, deg

SSVAV Compressor stator vane angle, deg

SBLC _r Bleed flow, percent

TABLEVII. - DESCRIPTIONOF TRANSIENTNAMELISTINTRAN

Variable array Default Description

name

Step input

PNTBLK -999 Print interval

Ramp inputs

PLABLK -999 PLA ramp input

ALTBLK Altitude ramp input

XMNBLK Mach number ramp input

WFBLK Fuel flow ramp input

AJBLK Nozzle area ramp input

FGVBLK Fan guide vane ramp input

SVABLK Compressor stator vane angle ramp input

BLCBLK _r Bleed flow ramp input

15
TABLEVIII. - HYTESSOBJECTMODULESTORAGEREQUIREMENTS

Program name Number of lines Direct module storage

of source code requirement (bytes) a

MAIN 80 l 288

ALTABL 109 2 616

ACTCRV(block data) 49 1 252

EMODEL 281 8 488

ENGPRN(block data) 38 264

FILTER 36 1 228

GVICAL I0 496

HFTA 16 404

INLET 60 2 316

ADD 7 548

SUB 7 548

MUL 9 760

SCA 7 516

MVCPRN(block data) 50 3 200

N2TABL 50 1 064

NUTIME 51 1 588

PRCMB 38 904

PRINT 87 5 672

PVAL 99 1 860

READIN 33 948

i RPSCH 120 3 568 I

SCURVE 267 4 732

SETUP 18 176

SNFMAP 73 1 544

SNISCH 21 960

SPRINT 68 2 I00

STDST8 77 1 884

TFHA 16 404

TRANS 83 1 632

UNBAR 77 1 940

SCALLA 15 400

Totals 1952 55 300

a4 Bytes per word.

16
TABLE IX. - STORAGEREQUIREMENTSFORBLOCKDATA

Block data Commonblock Commomblock Total block data

name storage storage

requirement a requirement a

ACTCRV ACTCRV 1252 1252

ENGPRN ENGPRN 264 264

MVCPRN MVCPRN 320 3200

EBLKS 1008

BASEV 64

STDV 64

MVCOUT 160

MATRIX 556

ENGOUT 120

ENCONTR 32

ESSIN 56

PTITLE 80

RAMREC 16

PLOTV 460

ENGPRN 264

aStorage requirement given in bytes.

TABLEX. - EXECUTION(CPU) TIME RESULTSFORHYTESSTEST CASE1

Group Module Accumulated Percent Number of Number of CPUtime

number name CPUtime, of total entries exits average

msec per call

1 MAINHYTS 4 0.II 1 1 4.000

3 READIN 6 .17 1 1 6.000

4 INLET 210 5.94 501 501 .410

5 STDST8 25 .71 1 1 25.000

6 PRINT 656 18.54 I01 I01 6.495

7 TRANS 179 5.06 1 1 179.000

8 SNFMAP 114 3.22 502 502 .227

9 N2TABL 202 5.71 1004 1004 .201

I0 FILTER 377 10.66 502 502 .751

II SCALLA 2 .06 I01 I01 .020

12 RPSCH 1264 35.73 1003 1003 1.260

13 EMODEL 499 14.10 502 502 .994

Timed CPUtotal 3538 I00.00

Overheada 1370

Job total 4908

aOverhead is the CPUtime required to calculate the CPUstatistics given

in table.

17

r--Highpressureturbine

I

Combustor--_

\\ _ [-Lowpressureturbine

Inlet Fan Compressor \ I I Nozzle

Station 0 2 2.5 3 4 4.5 5 6 7 8

Figure1.- Schematicrepresentatioonfa hypotheticatul rbofanengine.

24

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0 .5 1.0 1.5 2.0 2.5

Machnumber

Figure2. - Engineflight envelopewith engineoperating

points.
Yes

I'n+ allvariables ,ri_ No

[ Calculate

/Read ,L __.__ NI=F(WF) !

input data -- \ _/

J Calc

engine

condu+itlate io

fa

n

c

s

e

_

>

@ Jca,+,a+ PLA._=FINI)

I @

_ __,_, ___ Calculate [ >@

commanded =

I steadystate _ STDST8/ inputs

Calculate

__ Z_'_"_ basepoint

andsystem

matrices

"__" /results/ _ +

I +es,a,e J

spacemodel <

equations

' enerate =_@

transient _:

(_ Yes =_

Figure3. - BasicprogramflowthroughMAIN. Figure4. - Basicprogramflowthrough STDST.
Calculatebase I __

pointand

systemmatrices

Calculatestate I _@

spacemodel

equations

Incrementtime I =@

andupdate

requestedinput

_ Yes _rP_

Calculate I @

inlet _ =-

conditions

I

.

commanded _

inputs

l

Figure5. - BasicprogramflowthroughTRANS.
100 --

6O

d

20 er specifiedpoint

i I I I 4._L_l

0 .2 .4 .6 .8 1.0 I/ 5 10

Time,sec

Figure6.- UserspecifiePLA d inputransient- ISIexamptest l

case(See . tableIV.)

SIHPLIFIED ENGZNE5IHULATXON

HYPOTHETICALJET ENGINE

_ ENGINE RESPONSEVARZABLES_

TIHE 0,00000 O.IO000E O0 0,20000 0.30000 0._0000 0.$0000 0.60000 0,70000 0,80000 0.90000 ALT 0,00000 0.00000 O.OgO00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

SNN 0.00000 0.00000 0.00000 0.00000 0.00000 0,00000 0.00000 0,00000 0.00000 0,00000 PLA 2O.OOO 2O.'OOO 35.75O 51.500 67.25O 83.000 83.000 83.000 83,OOO 83.OOO

PO 1_.696 14.696 1_,696 16.696 1_.696 16.696 1_.696 16.696 14,696 1_,696 TO 518.69 518.69 518.69 518.69 518.69 518,_9 518.69 518,69 518.69 518,69

DPO 0,00000 0.00000 0.00000 O.O0OOO 0.00000 0,00000 0.00000 0,00000 0.00000 O.gO000 DTO 0.00000 0.00000 0.00000 0.00000 0,00000 0.00000 0,00000 0.00000 0.00000 0o00000

PT2 1_.696 1_.696 1_,696 1_.696 ]_.696 14,696 1_.696 1_.696 1_.696 14.696 ! TrZ 5]S.67 518,61 51a.67 51a.67 518.67 518,61 s18,67 518.61 518.67 51a.67

11 VO 0.00000 0.00000 0.00000 0.00000 0.00000 0,00000 0.00000 0,00000 0.00000 0.00000

12 £TARAH 1.0000 ],0000 1.0000 1,0000 1,0000 1.0000 1.0000 1.0000 1,0000 1,0000

13 _FHBH 113].! 1133.1 3267,5 509_.6 6787,9 ]0588. 105_8, 10588. 10588, 10588.

l_ AJCD 3.OOOO 3.OOOO 3.0OOO 3.OOOO 3.OOOO 3.OOOO 3.OOOO 3,OOOO 3.OOOO 3.OOOO

15 FGVPDS-25.OOO -25.OOO -25.OOO -25.OOO -25.OOO -25,OOO -25.OOO -25,OOO -25.OO0 -25,OOO

]6 SVAPOS-39.O33 -39.033 -3_.975 -21.9_Z -2.95O6 6.OOOO 6,OOOO 6.OOOO 6,OOOO 6.OOOO

17 BL¢ 0.00000 0.00000 0.00000 0,00000 0.00000 0,00000 0.00000 0.00000 0.00000 O,O0000

18 SNFAN 35_0.9 35_0.g 37Z_.9 _227.7 5125,9 6801.7 7856.3 8573.0 9061.6 9273.9

19 5NCOM 8695._ 8695._ 8977.2 9655.6 1O6O7. 1153_. 120_6. 12221. 12254. 12217.

20 TT_PLO 93.630 93.630 10_.83 131.83 169.25 196,79 203.91 206.35 207.33 _07._0

21 TT_SLO 66.27Z 66.272 77.389 ]02.55 135._8 163.03 172,08 172.01 169,22 166._2

2Z 5NFAN 3560.9 35_0.9 372_,9 _227,7 5125.9 680].7 7856,3 8573.0 9061.6 9273.9

23 5NCOH 8695,_ 8695._ 8977.2 9655.6 10607. 1153_. 120_6, 12221. 1225_. 12217.

2_ PT4 65._9_ 65._98 92.335 126.50 173,63 2_9.93 28O,98 311.87 32_,16 329.73

25 PT6 17.571 17.57! 18._62 19.751 23.779 32,_09 36.O8O _Z,7_2 _5.717 46._22

26 TT_5 565.79 565.79 13_2._ 1903.7 2158.7 237O.9 180_,8 1629.2 152_°4 151_.6

27 FNMX 1363.9 1363,9 ]822,7 2_20.8 _5_7.6 12762. 126O1. 12316. 11575, _1035,

28 5Nttc 0.68756 0.68156 0.5176q 0._53_9 0._186! 0.17661 0.21895 0.22693 0._2756 0,21267

_ REFERENCEPOINT SCHEDULES_

PLASS 2O.OOO 2O.OOO 35.75O 51.500 67.25O 83.OOO 83.000 83.OOO 83.OOO 83.OOO TT2SS 58.970 58.970 58.970 58.970 58.970 58,970 58.970 58,970 58,970 58.970

PT255 1_.696 1_.696 16,696 1_.696 ]_.696 1_.696 1_,696 1_.696 1_.696 1_,696 5HNSS 0.00000 0,00000 0.00000 0,00000 0.00000 0.00000 0.00000 0,00000 0.00000 0o00000

PHSNFSDSSCH -999, 0,35_0090 -09.395g._0009 -999. 0,6980055 -0999 .79_.005 -0999. ,8_966 00 -0999, ,9360053 -0999. ,9360053 -0999 .g36.0053 -g0.9939.60053 -09,936 _9.0053

SNT25C5S¢HCll 0.1576296g .70 0.1562969 2.70 0,6765 162._50 0.176186 2.705 0.175629_.707 0.8_6207 2.708 0.1862207.708 0.8_62. 207708 0.816207 2.708 0.816207 2.708

1 PTFT_$ISCCH_ 0O.35362 O.35362 0.56_96 0.6658_ 0,78236 O.95261 0.95261 O.9526! O.95261 0.9526! .119O9 0,11909 0.28_8 O,36931 0._6821 0.61_5! 0.61_5! 0.61_51 O.61651 0.61_5!

11 PT6M$_ 0._3516 0.13516 0,18832 0,23672 0.29766 0.3609_ 0.3609_ 0.3609_ 0.3609_ 0.3609_

12 TT_PLO 0,58519E-01 0.58519E-01 0.836_7E-01 0,956_0E-01 0.109_9 0.1297_ 0.Z297_ 0.1297_ 0._297_ 0.1297_

_3 TT_SLO 0.61620E-01 0._20E-01 0.61117£-0! 0,7051_E-0_ 0.81377E-01 0.972_E-01 0.9726_E-01 0,972_E-01 0.9726_E-01 0,9724_E-0!

1_ FNHXSH0,5_556E-01 0.5_556E-01 O,27886 O.36131 O,38377 O.63383 0._3383 0._3383 0._3383 0._3383

15 SM}ICSH 0.68756 O.68256 O.325O3 0.27_95 0.2_]50 O.2O965 O.2O965 O,2O965 O.2O965 O.2O965

26 _FHBSH 1133.1 1133.! 32_7.5 509_.6 6787.9 1O588. 1O588. 1O588, 10588. 1O588,

]7 AJSCH 3.OOOO 3,OOOO 3.OOOO 3.OOOO 3.OOOO 3.OOOO 3.OOOO 3.OOOO 3.OOOO 3.OOOO

18 FGVVSH -25.OOO -25.OOO =25.000 -25,OOO -25.OOO -25.OOO -25.OOO -25,OOO =25.000 -25.OOO

19 SVAVSH -39,033 -39.033 -3_.975 ~21,9_Z -2.9506 6.0000 6.0000 6.0000 6.0000 6,0000

2O BLCSH 0,00000 0.00000 0,00000 0.00000 0,00000 0.00000 0,00000 0.00000 0.0000_ 0,00000

Figure7. - Exampleoutputfor HYTESStest case.

1. Report No. 2. Government Accession No. 3. Recipienrs Catalog No.

NASATM-83561

4. Title and Subtitle 5. Report Date

January 1984

HYTESS- A Hypothetical Turbofan Engine Simplified Simul ati on e.PerformingOrganizationCode

505-32-6B

7. Author(s) 8. Performing Organization Report No.

Walter C. Merrill, Edward G. Beattie, Richard F. E-1940

LaPrad,Stephen M. Rock, and MuhammedM. Akhter lOWor . kUnitNo.

9. Performing Organization Name and Address

NationalAeronauticsand Space Administration 11Contract orGrant No.

Lewis ResearchCenter

CleveIand, 0hio 44135 13.Type ofReportand PeriodCovered

12. Sponsoring Agency Name and Address Techni cal Memorandum

National Aeronautics and Space Administration

Washington,D.C. 20546 14.SponsoringAgency Code

15S.upplementa_NWalter otes C. Merrill,NASA Lewis ResearchCenter; Edward C. Beattie and

Richard F. LaPrad,Pratt & WhitneyAircraft Co., UnitedTechnologiesCorp., 400

Main St., East Hartford,Connecticut06108;Stephen M. Rock and MuhammedM. Akhter,

Systems ControlTechnology,Inc., 1801 Page Mill Road, P.O. Box 10180, Palo Alto, California94303.

16. Abstract

This report is a users manual for a hypothetical turbofan engine simplified simulation. This digital simulation exists as FORTRANsource code. The program is

self-contained and was developed to offer those interested in engine dynamics and

controls research an efficient, realistic, and easily used engine simulation. The

engine is modeled using a state space formulation. Matrix elements within the

linear state space structure are nonlinear functions of various engine variables.

17. Key Wo_a (Suggest_ by Author(s)) 18. Distribution Statement

Simulation Unclassified - unlimited

Gas turbine engine STARCategory 07

State space

Dynamics

Controls

19. Security Claaelf. _f this m_) _. Secudty Cl_sslf. (of this _ge) 21. No. of _ges _. Pdce"

Unclassified Unclassified

"For Pie _ the NationalTechnical InformationSe_ice, Springfield,Virginia 22161

Space AAdministration eroou.EtioeOOK CnLF0 OO T0 11111.L1

Washington,D.C.

20546

Official Business

Penalty for Private Use, $300 Pottage end FeesPaid

Nationel Aeronautics and

Spice Administration

NASA-451

N/_A POSTMASTF.R: If Undeliverable (Section I S_

Postal Manual) l_J Not Return