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GAS TURBINE CYCLE CALCULATIONS:
EXPERIMENTAL VERIFICATION OF OFF-DEbIGN- POINT PERFORMANCE
PREDICTIONS FOR A TWO-SPOOL TURBOJET WITH VARIOUS AIR B3LEEDS
Deiahl -of Iflustrin'trons- Wthis documont miay be better
I studled on mlerofione
by
j ~M.S. CHAPPELL AND W. GRABE
E.P. Cockshutt, Head D. C. Mae PhailEngine Laboratory Director
SUMMARY
"As part of a continuing program of gasturbine cycle calculations, the Engine Laboratory ofthe National Research Council of Cimada has proposeda simplified method for calculating off-design-pointperformance of turbojet and turbofan engines, bothat sea level static and at altitude flight conditions.This method specifically implies constancy of com-ponent efficiencies and linearity of corrected massflow with corrected engine speed.I During a series of tests on a J-75 two-spoolturbojet engine, experimental data were gathered atpart-throttle conditions, and subsequently with com-pressor bleed extraction and with propelling nozzlearea change.
In general, the calculation routine yieldedvery good predictions of the part-throttle performanceof the datum engine. It was far less successful, how-ever, in forecasting the effects of compressor bleedextraction, propelling nozzle area change, and com-
4, binations of these perturbations to the basic cycle.
Lii! 'I
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"TABLE OF CONTENTS
Page
SUMMARY ................................................... (iii)
ILLUSTRATIONS .......................... ............ ........ . (v)
APPENDICES ......... ..................... ................ ..... (vii)
1.0 INTRODUCTION ........................................ 1
2.0 EXPERIMENTAL ARRANGEMENT ...................................
2. 1 Engine and Installation 1..................... ............. 12.2 Provisions for Bleed Extraction .................................2.3 Instrumentation ............................................... 32.4 Testing Technique ........................................... 4
3.0 DATA REDUCTION PROCEDURE ................................... 4
3. 1 Intake Air Mass Flow Rate 4................................ 43.2 Compressor Parameters ..................................... 43.3 Main Bleed Flow Parameters ............................... s3.4 Combustor and Turbine Inlet Conditions (A) ..................... 53.5 Turbine Parameters and Turbine Inlet Conditions (B) ............. 53.6 Propelling Nozzle Parameters and Overall Engine Performance .... 5
4.0 THE OFF-DESIGN-POINT PERFORMANCE PREDICTION PROGRAM ... 6
5.0 CORRELATION OF EXPERIMENTAL AND COMPUTED PERFORMANCEOF THE BASIC ENGINE ......................................... 6
5.1 Technique of Describing Anti-Surge Bleeds .......................... 75.2 Matching Computed Performance to Measured Data .............. 7
5.3 Implications of the Assumed Linear Relation Between Mass Flowand Low Pressure Spool Speed ............................... 9
5.4 Implications of Assumed Constant Compressor Efficiency ......... 9
6.0 COMPUTED AND MEASURED EFFECTS OF BLEED EXTRACTIONFROM THE BASIC ENGINE ..................................... 10
7.0 COMPUTED AND MEASURED EFFECTS OF INCREASED PROPELLINGNOZZLE AREA WITHOUT BLEED EXTRACTION ................. 13
8.0 COMPUTED AND MEASURED EFFECTS OF INCREASED PROPELLINGNOZZLE AREA WITH BLEED EXTRACTION ............................ 14
9.0 CONCLUSIONS . .................................................. 15
10.0 REFERENCES ................................................... 16
(iv)
ILLUSTRATIONS
Figure Page
1 J-75 Turbojet in No. 4 Test Cell .......... 17
2 Anti-Surge and Main Bleed Extraction Piping Configuration ....... 18
3 Propelling Nozzle and Bleed Air T-Nozzle ...................... 19
4 General Assembly of J .75 Engine with Provision for Bleed AirExtraction ......................... ...... t .......... 20
5 Sectional Elevation of No. 4 Test Cell Showing J-75 Installation . 21
PERFORMANCE OF THE BASIC J-75 ENGINE
6 H.P. vs L.P. Compressor Speed ........................ 22
7 Air Mass Flow Rate vs L.P. Spool Speed ................. 23
8a L. P. Compressor Pressure Ratio vs L. P. Spool Speed 24
8b L. P. Compressor Temperature Rise vs L. P. SpoolSpeed .............................................. 25
8c L. P. Cumpressor Isentropic Efficiency vs L. P. Spool Speed .. 26
9a H. P. Compressor Pressure Ratio vs L. P. Spool Speed ..... 27
9b H.P. Compressor Temperature Rise vs L. P. SpoolSpeed........................................... 28
9c H.P. Compressor Isentropic Efficiency vs L, P. SpoolSpeed .................... 29
10a Overall Compressor Pressure Ratio vs L. P. Spool Speed ... 30
10b Overall Compressor Temperature Rise vs L. P. SpoolSpeed .............................................. 31
10c Overall Compressor Isentropic Efficiency vs L. P. SpoolSpeed .............................................. 32
11 Fuel Flow vs L.P. Spool Speed .......................... 33
12 Turbine Inlet Temperature vs L. P. Spool Speed ........... 34
13 Turbine Outlet Temperature vs L. P. Spool Speed .......... 35
14 L. P. Turbine Outlet Pressure [E. P.R.] vs L. P. SpoolSpeed .............................................. 36
(v)
ILLUSTRATIONS (Cont'd)
Figure Page
PERFORMANCE OF THE BASIC J-75 ENGINE (Cont'd)
15a Thrust vs L.P. Spool Speed ............................. 37
15b Specific Thrust vs L.P. Spool Speed ...................... 38
16 Specific Fuel Consumption vs L. P. Spool Speed ........... 39
17 Specific Fuel Consumption vs Percent Maximum Thrust .... 40
BLEED EXTRACTION
18 Measured Main Bleed Flow Rate vs L. P. Spool Speed ......... 41
19 Bleed Influence Coefficients vs L. P. Spool Speed .......... 42..4
20 Specific Fuel Consumption Influence Coefficient vs PercentageMain Bleed for Various Engine Speeds .................. 43
COMPARISON OF MEASURED AND PREDICTED EFFECTS OFMAIN BLEED EXTRACTION
21 L. P. Compressor Pressure Ratio vs L. P. Spool Speed 44
22 H.P. Compressor Pressure Ratio vs L. P. Spool Speed 45
23 Fuel Flow Rate vs L.P. Spool Speed ................ ..... 46
24 Turbine Inlet Temperature vs L. P. Spool Speed .......... 47
25 Turbine Outlet Temperature vs L.P. Spool Speed .......... 48
26 Thrust vs L. P. Spool Speed ............................ 49
27 Specific Thrust vs L. P. Spool Speed ...................... 50
28 Specific Fuel Consumption vs L.P. Spool Speed ............ 51
PROPELLING NOZZLE AREA CHANGE
29 Influence Coefficients Resulting from Change I n PropellingNozzle Area vs L.P. Spool Speed ...................... 52
COMPARISON OF MEASURED AND PREDICTED EFFECTS OFCHANGE IN PROPELLING NOZZLE AREA
30 L. P. Compressor Pressure Ratio vs L. P. Spool Speed ..... 53
31 H.P. Compressor Pressure Ratio vs L. P. Spool Speed 54
(vi)
ILLUSTRATIONS (Cont'd)
Figure Page
COMPARISON OF MEASURED AND PREDICTED EFFECTS OF ICHANGE IN PROPELLING NOZZLE AREA (Cont'd)
32 Fuel Flow Rate vs L. P. Spool Speed .................... 55
33 Turbine Inlet Temperature vs L.P. Spool Speed .......... b6
34 Turbine Outlet Temperature vs L. P. Spool Speed .......... 57
35 Thrust vs L.P. Spool Speed ............................ 58
36 Specific Thrust vs L.P. Spool Speed ..................... 59
37 Specific Fuel Consumption vs L. P. Spool Speod ........... 60
COMPARISON OF MEASURED AND PREDICTED EFFECTS OFMAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
38 L.P. Compressor Pressure Ratio vs L.P. Spool Speed ..... 61
39 H. P. Compressor Pressure Ratio vs L. P. Spool Speed 62
40 Fuel Flow Rate vs L.P. Spool Speed ...................... 63
41 Turbine Inlet Temperature vs L. P. Spool Speed ........... 64
42 Turbine Outlet Temperature vs L.P. Spool Speed ...... . 65
43 Thrust vs L.P. Spool Speed ............................. 66
44 Specific Thrust vs L.P. Spool Speed ........... ...... 67
45 Specific Fuel Consumption vs L. P. Spool Speed ............ 68
APPENDICES
Appendix Page
A J-75 Data Reduction Program: Sample Raw Data and OutputSheets ................................................... 69
B Sample Input and Output Sheets from the Off-Design-Point (O.D. P.)Performance Prediction Program .................. ..... 73
I(;-
(vii)
GAS TURBINE CYCLE CALCULATIONS:EXPERIMEN7TAL VERIFICATION OF OFF-DESIGN- POINT PERFORMANCE
PREDICTIONS FOR A TWO-SPOOL TURBOJET WITH VARIOUS AIr. BLEEDS
1.0 INTRODUCTION
The Engine Laboratory is engaged in a continuing program of generatingGa Turbine Cycle Calculation routines of sufficient flexibility and rigour to have wideapplicability for aircraft performance studies. References 1, 2, 3, and 5 are membersof ýthe series of reports describing these cycle analysis programs. In particular,Reference 1 describes the performance prediction program for turbojet and turbofanengines operating at part-throttle, both at sea level static and at altitude flight conditions.The predictions are based on co atant' component efficiencies and a linear relationbetween corrected air mass flow and corrected L. P. compressor speed. Furtherdetails are given in Section 4.0.
As part of another investigation (Ref. 6) a two-spool turbojet engine wasinstalled in the Laboratory's No. 4 Test Cell during the summer of 1970 (Fig. 1). Thisprovided an opportunity to compare the performance predictions of the Off-Design-Point(0. D. P.) progrdin (Ref. 1) with experimental data. In addition to the comparison ofmeasured and predicted part-throttle performance, the current investigation comparesthe observed and calculated effects of substantial bleed extraction from the H. P. com-pressordeliveryplenum, of variations in propelling nozzle area, and of combinationsof these two perturbations to the basic engine cycle.
2.0 EXPERIMENTAL ARRANGEMENT
2.1 Engine and Installation
The experimental data for this verification were measured on a J-75/P-3two-spool turbojet. This early version of the J-75 engine series comprised a ten-stageL. P. compressor driven by a two-stage turbine, and a seven-stage H. P. compressordriven by a single-stage turbine. Twin anti-.surge bleeds were fitted between the com-pressor spools to vent approximately 6% of the L. P. compressor mass flow at L. P.spool speeds below about 78%, (Fig. 2). The main combustor was of the can-annulartype. The engine was fitted with an afterburner and a two-position propelling nozzle(Fig. 3), however the afterburner was not used during this test program.
The engine was installed in No. 4 Test Cell during the summer of 1970, asIllustrated in Figure 1.
2.2 Provisions for Bleed Extraction
The term "Main Bleed" as used in this report refers to the extraction ofH. P. compressor delivery air for purposes noL directly related to Lhe operation of theJ-75 engine. This bleed was in addition to the anti-surge bleeds (described in Section 2.1)that were necessary for the proper functioning of the engine.
Main bleed air was extracted from thw diffuser between the H.P. compressordelivery annulus and the combustor inlet plenum. Four separate ports were fitted asstandard equipment on the J-75 engine. Two 3-inch diameter offtakes were provided
S. .. .'I ~ J•II + .,. -. , .-...- .
TA1iLI: I
INSTRUMIENTATION4
IAIN PARAMETER MEASURED TPS AND UflliTION I INSTRUMENT TYvPE iI"101 1,1TIh.
THIERMOJDYNAMtIC PARIAMETERS
Barometric Pressure Mercury Baomter i eading go 1to fl1lig 0. S0S1tig
A Test CalellDepresslooe open Tubs an Toot Call Wall Manometer 0 to l011,c) O0in10 Foot Forward of Enginie
Iptalke liatlo Pressutre 4 W*ll Too*e (Ganged) at the Manometer 0 to 8011,110 0, 04"1,00Holilmoath Exit
Inakes Tolal Temperature 4 Thermistoe Proaes at tie Direct Beretinag -40 to +Isow-, 0. 1CiBellmoith Exit Ctolaromotor
L. P. Compressor 5- ,Poita Radially Averaging Itaurriox Cause 0 to 141 psig 0.,1 pat
L. P. Vompressor 2 Single FE/CON Ttiernoooople ltielotl Pyrmomter ti to 4501C 1.0-CDelivery Total Temperature Probes (at 1/3 anil 2/3 itadit)
Reasiout iteparaetly
H, lP. Comptressor 2 G-Polint Ituldilaly Averaging Btourdon Gauge 0 ito 200 pal% 1.0 PotDelivery Total Pressure Bakes (COaxied)
H, P. Compressor 4 Single lE/1CON Thermocootple Bistitol 1yrometer it to 450'C 1.011Delivery Total Temperature Probes (at 1/2 end 2/l0 Hadti))
Reoadouit Separately
L.b P. Turbine outlet 3 11-Polot Raiallaly Averaging iloirdon Clauge a to 2001t111 0. 1 hlgTotal Presauro Prober (Ganged)
L.Ill Turbine outlet a. 4 Stngie Cit/AL lThe rrnortple Bisto~lo Pyrometer it to 1200-C 2.01CTotal Temperature Probe* at bttd-itadlua (Gensedt)
b, :1 5-FaltRad tiially Averagingt litrisol Pyrometer 0 to 12110'C 2.01CCR/AL Thermocoutple Probes
MucPI'LLANPI.'tiu PERtFORIMANCE 11AIWIAMTNItS
L. P. Spool Spaeed Aircraft Tachammatorlexoretor Alroiot. Diat Elauga 11 to tIall I0. I'l
li, P.Spool Speed Aircraft Tachometer Geherstor Airoteft Dialt lauiex 0 to 10011, 0. lIT
A Anti-Burge Btlood 2 20-totnt Avieragin fa hoor Mianometers Uito tlt"1-t0.114-tTotai Pressuore Separate Rteadouts Port and
Starboard
Anti-Surge Blood Slngle Point FlE/L'tN Thermooouple itriolni i'yromola 1) to 460*0 1.010TMli Temperaiure Probe tn Keith of Two t1l0"I Mlims xdii-llntgih
Foot Flow Flats Trortle Meter In L.. P. tIne Prequenoy C)onverter 0 to tO, 000 t0 hl/hr
1hml of Floatfing Toat lBed
Meafuriag Orifice single Wall TlAP Itourtm [lAuga 0 tn 141 ltwi 0.,1 ptwgUpstream Pressure
Mesuoring Orifice i-Diameter Walt Talps Manometer tC 1' h. 5-- 0514tDifferential Pressure
O1-tIIt0e Plate M~etal Stiagle itorto FX/C0N Hlmreto Ps-ronoter Sb to 4tj*Temperature Thtermocouple Probe
Bleed Total Pressure Sinagle Ptilot at Raditus Jiourtion 1)501)0 0)to 200 petS 1.0 PetE
OFVIL4TKIC0Ai P'ARAMtETER$~
Fool Istle Pressuore watt Tsp at Eatry to EngiAne llouril" out Gag (to 100 polo 1.0 palFoci System
Otil Temnperature Ttormwouxplu Proliv in Arooseory Galvanootootr 0 to. 2600. I.O*C
otl Pnwreosot .It blump I n o Itoordi 1iaoao 1) to ISO wImg l.i ret
Oil Tank Breather Gil Tanb Vent Lený Manometer 0 to 4110111-3t 0. D5'i.1 IProessure
V~lbrittue SetamIc Mims Acolr'rrnieterr luR"tegattithter 0 to 5 lth, 0. 1 thoouIatake, Interepuol, Mountoi In ~tl,, Itorionatal with lI)tto file.-It. P. C( uiproeear Plaune at ali Four Statics. ptlrntrl lmet Hdoo~t
4 Delivery. Tu~rbine _____. ___
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for cabin pressurization and air conditioning. Two additional l-Inch diameter portswere provided to supply anti-icing air for protecting the intake components of theengine. Only one of tbese latter two ports would normally be used, the other beingprovided for alteniative accessory locations. To achieve the main bleed flow ratesrequired for the companion investigation, all four ports were connected to a header
plenum as bhown in Figures 2 and 4. Part way through the program a fifth port, iden-tioal with the two cabin bleed offtakes, was added in an attempt to increase the mainbleed flow rate further.
Main bleed air was discharged laterally through the two branches of theT-nozzle shown in Figures 3 and 4. This nozzle configuration was chosen to eliminate .axial thrust generated by the main bleed efflux.' Bleed flow rate was governed by thesize of the two discharge orifices in the T-nozzle.
2.3 Instrumentation ITable I shows the instrumentation fitted to the engine for this test program.
Station coding is definea in Sketch A. Figure 2 illustrates the anti-surge bleed extensionpipe (port side) with the total pressure rake fitted. Figure 4 indicates the location ofthe main bleed flow measuring orifice and other bleed flow instrumentation points.
A C ML OMH . C0MTBH .TU .P T N
I
NI kj 55 T R H. E~T1
B TaEON K. S IToN L RAN L
A4________________
MAIN BLEED EXTRACTIONII
ANTI-SURGEBL EED
SKETCH A: THERMODYNAMIC CYCLE SHOWING BLEED EXTRACTION POINTS
iV
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2.4 Testing Technique
A Calibration Run was made from idle to Military power in steps of approxi-mately 5% L. P. spool speed. Subsequent tests were then performed with successivelyincreased bleed nozzle discharge orifices.
In all cases the li'kiting indicated turbine outlet temperature of 595°C wasobserved. Despite low ambient temperatures, this limit restricted the maximumoperating speed whenever main bleed flow rates exceeded about 6% of the engine intakeflow rate.
Later in the program, the engfi.e propelling nozzle area was increased byadjusting the "closed position" stops'(Fig. 3). This decreased the observed turbine..outlet temperature.. and. thus permitted operation to higher speeds and higher. bleedflow rates.
A sample "Raw Data" log sheet is incorporated in Appendix A.
3.0 DATA REDUCTION PROCEDURE
The data reduction routine utilized the rigorous thermodynamic techniques"outlined in Reference 2, as well as temperature and fuel-air-ratio dependent thermo-dynamic properties for the working fluid as outlined in Reference 5, to describe theprocesses within the Various engine components. These techniques were used directlyin evaluating parameters for which all required variables were measured, and indirectly,by trial and error, to establish values for variables that were not measured, Allexperimental data were corrected to standard-day inlet conditions of 15°C and 29.92" Hg.
The program was coded in Fortran IV for the NRC IBM System 360 TSS."Sample raw data and output sheets are included heyrein as Appendix A. Raw input datawere tabulated together with the computed cycle parameters on a single output sheetfor each test point. The output format was arranged in a style similar to that of thecycle analysis programs of References 1 and 2.
3.1 Intake Air Mass Flow Rate
Engine inlet air flow rate was calculated from total temperature and staticpressure measurements taken near the oxit from the entry bellmouth. Total pressurewas determined from the local barometric pressure and the measured test celldepression. Inviscid one-dimensional flow assumptions were used initially. Later, acorrelation was introduced to account for two-dimensional flow, based on an analysisof the flow in the bellmouth performed by Davis at Carleton University (Ref. 4).
3.2 Compressor Parameters
The L. P. and H. P. compressor pressure ratios and Isentropic efficiencieswere calculated directly from total pressure and total temperature measurementstaken at inlet and exit from these components.
Anti-surge bleed flow rate was computed from total temperature and totalpressure measurements made at the exit planes of the extension tubes fitted to the
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bleed ports (see Fig. 2). Port and starboard flow rates were calculated separately andthe sum was subtracted from the intake mass flow rate to give the H. P. compressorflow rate.
Work requirements for both compressor spools were determined from theappropriate temperature rise and mass flow rate data.
3.3 Main Bleed Flow Parameters
The main bleed flow rate was measured by a British Standard sharp-edgedorifice situated between the prerequisite lengths of straight duct in the bleed dischargepipe (see Fig. 4). Total temperature and pressure were measured upstream of thisorifice plate. A theoretical maximum available bleed horsepower was computed byassuming isentropic expansion from the bleed orifice inlet conditions to ambient totalpressure. These data are grouped separately on the output sheet (see Appendix A).
3.4 Combustor and Turbine Inlet Conditions (A)
Combustor efflux conditions were predicted from H. P., compressor outletmeasurements using the measured fuel flow rate (with an Effective Calorific Value inaccordance with Ref. 5) and an assumed total pressure loss of 5%.
3. 5 Turbine Parameters and Turbine Inlet Conditions (B)
Total temperature and total pressure were measured at the outlet of the L. P.turbine. The work requirements for the two compressor spools were used in conjunc-tion with the turbine mass flow rate (adjusted from the H. P. compressor flow rate toaccount for main bleed extraction and fuel addition) to give a second estimate of theinlet temperature to the H. P. turbine. This value was printed below the value obtainedfrom the combustor calculations of Section 3.4, and agreement to within about 3% wasobtained in most cases.
The H. P. turbine inlet pressure was determined from the measured L. P.turbine outlet pressure by adjusting the assumed turbine efficiencies to give closeagreement with the v•alue derived from the nombustor calculations of Section 3.4 (i. e.95% of the H.P. compressor delivery pressure). No means were incorporated forchanging turbine efficiencies in relation to engine speed and a constant value of 85%isentropic efficiency was found to give agreement to within about 5% over -the usefuloperating range of the engine.
3.6 Propelling Nozzle Parameters and Overall Engine Performance
Calculated thrust was derived from measured values of L. P, turbine outlettemperature, nozzle mass flow rate, and (hot) final nozzle area, together with a thrust-multiplier type of nozzle 'efficiency' that accounted for real-flow deviations from thetheoretical isentropic expansion process. An 'efficiency' value of 96% gave goodagreement between calculated and measured thrust at all significant engine operatingspeeds. Th3 nozzle-inlet total pressure determined during the thrust calculations wascompared with the measured L, P. turbine outlet pressure to estimate the loss of totalpressure in the afterburner tailpipe.
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Specific thrust and specific fuel consumption completed the engine cycleprintotit, as shown in Appendix A.
4.0 THE OFF-DESIGN-POINT PERFORMANCE PREDICTIQN PROGRAM
The off-design-point (O, D. P. ) cycle analysis program is one of the seriesof gas turbine cycle calculation routines generated at'the Engine Laboratory. It jpredicts cycle parameters and engine performance for a range of decreasing enginespeeds, both at sea level static and at altitude flight conditions. It is described fullyin Reference 1 and hence only a brief outline will be presented herein.
The fundamental thermodynamic routines and the component subriUtines arethe same as used in the design point (D. P. ) program of Reference 2. The O.D.P.program first calculates the 100% speed, sea level static case for the engine cyclespecified by the input data (see Appendix B). The routine then resets '.he intake'parameters to the altitude flight conditions specified in the input data and generatesthe 100% speed, altitude case. During this and all part-throttle cases, the turbineand propelling nozzle areas are fixed at the values established during the 100% speed,sea level static case. The program iterates throughout the entire cycle calculationuntil the areas are matched at each part-throttle speed. To aid convergence, thedifferential analysis technique of Reference 3 is used to predict the changes -requiredin the major engine variables for each iteration.
The major assumptions incorporated within the O.D. P. program are:
(a) Component (compressor and turbine) efficiencies remain constant at thedesign point values
(b) Combustor efficiency, pressure losses, and nozzle thrust "efficiency"remain constant at the design point values
and (c) Corrected engine intake mass flow rate varies in direct proportion to thecorrected L. P. compressor rotational speed.
Appendix B contains samplc O.D. P. input and output sheets to illustratetheir respective formats.
5.0 CORRELATION OF EXTERIMENTAL AND COMPUTED PERFORMANCE OFTHE BASIC ENGINE
The term "Basic Engine" is used throughout this report to denote thegeometric configuration of the Y-75/P-3 engine as originally tested and matched to thecomputed cycle. Perturbations to the Basic Engine cycle were:
(a) Extraction of (massive) bleed air from the H. P. compressor outletdiffuser casing
I (b) Increase of propelling nozzle area
and (c) Combinations of (a) and (b).
I
I7
iThe thermodynamic cycle is depJ.cted schematically in Sketch A, Section 2.3,including both anti-surge and main bleed extractions. It will be recalled that the anti-surge bleed from the L. P. compressor is required for normal engine operation atspeeds below about 78%, irrespective of any additional main bleed air extraction fromthe H.P. compressor outlet diffuser.
5.1 Technique of Describing Anti-Surge Bleeds
'The current version of the 0. D. P. program has the capability of analysingan engine cycle in which different quantities of overboard bleed are extracted from theoutlete of bobh compressor spools, at sea level static and at altitude flight conditions.The turbine and propelling nozzle areas are established for sea level static intakeconditions with the bleed extraction quantities specified for the sea level static case.These areas remain fixed for all throttle settings at the altitude intake conditions andthe altitude bleed quantity specified. This program feature provided simulation of theanti-surge bleeds on the J-75 engine, by processing two dual calculations (see below)both with the same (sea level static, no anti-surge bleed) base cycle. A negligiblealtitude of 15 feet was specified for the second part of each cycle in order to permit theincorporation of the interspool bleed at the lower speeds.
CYCLE I (a) Sea Level No A/S Bleeds 100% Speed
(b) 15 ft Altitude No A/S Bleeds 100% Speed to 80% Speed
CYCLE II (a) Sea Level No A/S Bleeds 100% Speed(b) 15 ft Altitude 6.1% A/S Bleed 100% Speed to 40% Speed
t (100% to 80% Discarded)
Cycles I(a) and 11(a) are of course identical. Cycle I(b) describes engineperformance at part-throttle speeds down to 80% where the anti-surge bleed ports are• closed. Cycle II(b) describes engine performance at part-throttle speeds of 75% and
* •below where approximately 6. 1% anti-surge bleed is extracted from the L. P. com-pressor delivery plenum.
4 This technique was used to describe the extraction of anti-surge bleed airfrom the L.P. compressor in all J-75 cycles, both with and without main bleedextraction from the H. P. compressor.
5.2 Matching Computed Performance to Measured Data
Figures 6to 17 show the comparison betweenthe measured engine parametersand those predicted by the 0. D. P. program for part-throttle settings down to 40% L. P.spool speed. The inputs for the Design Point cycle were selected to give reasonableagreement with the experimental data at the higher L. P. spool speeds (80% to 100% N1).The thermodynamic parameters of the most representative Design Point cycle arelisted, together with the comparable experimental values, in the following Table.
FI 11111 T ill'i ,I-!: ! H !!•:! '" i' ,•,.,I
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PARAMETER EXPERIMENTAL D. P. CYCLE
L.P. Compressor PR 3.80 3.80r ,j,,t 0.85 ave 0.85
PL (0.00) 0.00
Anti-Surge Bleed Flow 6.1% ave @:5 78% N1 .10% @ < 78% N1
H.P. Compressor PR 3.09 3.09
0.90 ave 0.91
PL (0.00) 0.00
Combustor PL '(0.05) 0.05
n,, (0.98) 0.98
Turbine Inlet Temperature a 1187°K 1173"Kb 12010K
H.P. Turbine i lent (0.85) 0.85, (1.00) 1.00
PL (0.00) 0.00
L.P. Turbine (0s,85) 0.857lm.ck (1.00) 1.00
PL (0.06) 0.06
Propelling Nozzle 1% (0.96) 0.96
Performance at 100% N1
Specific Thrust 62.41 lbf/lb,/sec 64.08 lbf/lb,/sec
Specific Fuel 0. 868 lbm/hr/lbf 0. 852 lbm/hr/lbfConsumption
Experimental cycle values in parentheses were either inferred from measurements ofother parameters or assumed.
No account was taken of accessory drive power extraction from either spool or forextraction and return of turbine disc cooling airflows.
It can be seen from Figures 6 to 17 that very close agreement was achievedbetween most measured and computed part-throttle data down to the speed at which theanti-surge bleed valves opened (about 78% N,). The step-change in nearly all parameters
at the onset of anti-surge bleed flow was also accurately predicted by the O.D.P.program using the technique described in Section 5. 1. The considerable scatter ofcompressor efficiencies, which were derived from measured engine data, is discussedin Section 5.4.
5.3 Implications of the Assumed Linear Relation Between Mass Flow and LowPressure Spool Speed
Figure 'Y shows the measured variation of intake air mass flow rate with.L. P, spool speed compared with the O.D. P. program approximation of linear propor- ..tionality. One can see that, for this two-spool turbojet engine, the approximationunderestimated the air mass flow rate by up to about 3% in the 100% to 75% speedrange. Below 75% speed, the approximation coiitinuously overestimated the intakeflow rate, the discrepancy reaching a maximum of 7% at 40% L. P. spool speed.
The effect of this imperfect correlation on mass-flow-rate-dependentparameters such as fuel flow rate and thrust can be noted on Figures 11 and 15a re-spectively. Both parameters show increasing differences between experimental andcomputed values as engine speed decreases, the latter values being greater in bothcases. However, the absolute magnitude of the error L. large, amounting to lessthan 3% at useful engine speeds of 75% and above.
Greater discrepancies in mass-flow-dependent performance parameters maybe expected in high bypass ratio turbofan engine cycles where a significant proportionof the total engine performance is due to the unheated bypass stream.
5.4 Implications of Assumed Constant Compressor Efficiency
The experimentally determined values of L. P., H. P., and overall compressorefficiencies exhibited considerable scatter, as shown on Figures 8c, 9c, and 10c. Anaverage isentropic efficiency, biased toward the higher operating speeds, was selectedfor the D. P. cycle. This value was converted to a polytropic efficiency for input intothe O.D.P. program and the corresponding isentropic efficiencies were computed ateach throttle setting (pressure ratio) for this fixed D. P. polytropic efficiency.
A strong decline in the measured efficiency of the L. P. compressor spoolfrom 80% to 100% engine speed (Fig. 8c) was evident, and yet the part-throttlepredictions of L. P. pressure ratio (Fig. 8a) and L. P. temperature rise (Fig. 8b)based on the constant polytropic efficiency are acceptably close to the measured values,even at engine speeds as low as 40%.
The measured values of the H. P. compressor efficiency do not show asstrong a trend with engine speed (Fig. 9c) and hence the constant polytropic efficiencyprediction more closely approximates the scattered experimental data. Moreover,excellent agreement between the measured and predicted values of pressure ratio andtemperature rise across the H. P. compressor spool can be noted from Figures 9a and9b at engine speeds down to about 70%. Below this speed, however, the 11. P. compres-sor pressure ratio predicted by the O.D.P. program remains substantially constant
whereas the experimental values continue to fall significantly. This suggests that, infact,' the H. P. compressor efficiency drops more than the predicted data indicate inthis low speed region. It will be noted also from Figure 6 that the O.D. P. program pre-dicts considerably higher H. P. spool speeds than were measured at L. P. spool speedsof•70% Rnd below.
The predicted overall compressor characteristics shown on Figures 10a, lOb,and 1Oc agree closely with the' experimental values. Unlike the individual compressorcharacteristics, these overall experimental data are independent of measurements
made at the interspool station (,&) and the scatter is noted to be considerably less,even for the efficiency values shown on Figure bOc.
No experimental data were obtained to permit calculation of individual oroverall turbine efficiencies. As detailed in Section 3, the assumed values of turbineefficiencies used in the experimental data reduction program were adjusted to give areasonable match between turbine inlet pressures determined from upstream anddownstream measuring stations. The same turbine efficiency values were used in theO.D.P. program simulation of the engine cycle.
6.0 COMPUTED AND MEASURED EFFECTS OF BLEED EXTRACTION FROM THEBASIC ENGINE
The major engine parameters affected by the extraction of main bleed airfrom the H. P. compressor delivery plenum are:
1. L. P. and H.P. compressor operating lines2. Turbine inlet and turbine outlet temperatures3. Thrust4. Specific fuel consumption.
In general terms, main bleed extraction will: increase the surge margin ofboth L.P. and H.P. compressors; increase both turbine inlet and turbine outlettemperatures (and the turbine temperature drop); decrease specific thrust based onthe inlet air mass flow rate; and increase the specific fuel consumption.
Two experimental runs were made with main bleed air extraction from theH. P. compressor delivery plenum of the Basic Engine. Total geometric areas forthe two T-nozzle orifices (recall Section 2.2) were 6.28 sq. in. and 14.14 sq. in.yielding average bleed mass flow rates of 3.6% and 5.9% of engine intake mass flowrespectively (see Fig. 18). Data from these two tests were reduced by the DataReduction Routine described in Section 3.0, and were compared with experimental datafrom the calibration runs of the Basic Engine to obtain the measured effects of mainbleed extraction cn various engine parameters.
Predicted effects of main bleed extraction were obtained by comparing theO.D.P. program ouputs for the basic engine and for the engine with various fixedpercentages of main bleed air. The same technique of manipulating the O.D.P.program was used to describe main bleed extraction from the H. P. compressor aswas used to describe the anti-surge bleed extraction from the L. P. compressor(Section 5.1). Four sets of dual cycles were processed to yield values for 3.7%, 5.0%,6.0%, and 10. 0% main bleed flow rate.
-11-
A/S MAIN L.P. SPOOLBLEED BLEED SPEED RANGE
CYCLE A 1) Sea Level NIL NIL 100% i2) 15' NIL MB% 100% to 80%
CYCLE B 1) Sea Level NIL NIL 100%
2) 15' 6.1% MB% 100% to 40%(100% to 80% discarded)
where MB% = 3.7%, 5.0%, 6.0%, 10.0%
As explained in Section 5. 1, this technique maintained the basic engine valuesfor turbine and propllling nozzle areas during the part-throttle cycles with dual bleeds.
Comparisons of the predicted and measured effects of main bleed extractionwere made for the engine parameters listed at the beginning of this Section. Bothdimensional and non-dimensional data were compared. The latter are presented interms of 'Influence Coefficients' (Wes), which were defined as follows:
A mB/.% -AJBASIC ENGINE I
I0BLEED EDL ~ ,BASIC ENGINEL_ "• •NO BLEED
M B %MAIN BLEED
where: J represents any engine parameter
and MB % is the percentage of main bleed
The influence coefficient describes the percentage change in the engine
parameter A for one percent main bleed extracted from the H. P. compressordelivery plenum. At very small bleed flow rates these influence coefficients would beconstant regardless of the percentage bleed. However, calculations for bleed flowrates of interest showed this not to be the case for some parameters, particularlyturbine inlet and turbine outlet temperatures and specific fuel consumption (Fig. 19).Hence it was necessary to compare predicted and experimental values using theinfluence coefficients for the correct (experimentally determined) percentage mainbleed. To facilitate this approach, influence coefficients for the relevant engineparameters were determined from the O.D.P. outputs for 3.7%, 5.0%, 6,0%, and 10.0%main bleed flow rates using the general form of equation (1) above for various engine Jspeeds. These values were plotted as shown in Figure 20 (using the specific fuel con-sumption influence coefficients as an example). Individual values were then read off forthe speed and main bleed flow rate conditions measured during the experimental tests(e.g. Fig. 18).
:I
-12-
The calculation procedure was tabulated as Indicated In the following example (for the specificfuel consumption response).
J-75t COMPARISON OF MEASURED AND PREDICTED RESPONSETO MAIN BLEED EXTRACTION
(Specific Fuel Consumption)
o% PREDICTED PREDICTED MEASURED MEASURED/N, BLEED - MEASURE
BASIC ENMOSR,(X.P.) .,., A AA LAAEXP. BLEED ~ I
40 3.02 2.900 1.4880 1.3867 +0. 1313 -0.1013 -2.254
50 8.10 2.760 1.0585 N/R 0.0906 - -
0L 60 3.25 2.592 0.9020 0.9663 0.0760 0.0643 2.193
70 3.47 2.375 0.8375 N/R 0.0690 -
75 3.58 2.265 0.8235 0.8923 0.0668 0.0688 2.334
so 3.64 1.980 0.7740 0.8356 0,0558 0.0616 2.186
.85 3.70 1.840 0.7880 0.8483 0.0536 0.0603 2,068
0 90 3.76 1.740 0.8090 0.8689 0.0529 0.0599 1.969U - - 063.2020
95 3.80 1.655 0.8350 Rdg, Error 0.0525 - -
100 3.83 1.590 0.8660 0.9294 0.0527 0.0634 1.911
RUN 2 SCF
COLUMN / Experimental percentage bleed read from Figure 18 for the appropriate %NI and
Run No.
COLUMN A Predicted influence coefficient read from Figure 20 for the speed and percentage bleed
of Columns & and ,
COLUMN A Specific fuel consumption of the basic engine without main bleed at the appropriatespeed read from calibration plot (Fig. 16).
COLUMN A Specific fuel consumption of the engine with percentage bleed per Column & readfrom the Data Reduction Routine output sheets for the appropriate Run No, and speed,
COLUMN , Predicted change ,n spedific fuel consumption obtained from the product of Columnas8
a,.nd&.
COLUMN & Measured change in specific fuel consumption obtained from the difference of
Column A - Column A.ColumnA
COLUMN &j Measured influence coefficient obtained from C m
Column A v Column A
-13-
Dimensional values from Columns L• and A , and influence coefficients
from Columns & and & were plotted against L. P. spool speed from Column & asshown in Figure 28. Figures 21 to 28 illustrate the comparison between measured andpredicted response of other salient engine parameters in the same format.
Both dimensional changes and influence coefficients related to the L. P.compressor pressure ratio show good agreement with predicted values at all usefulengine speeds (see Fig. 21). Although analytical and experimental H. P. compressorpressure ratio responses rhow a common trend (see FIg. 22) the absolute values arein reasonable agreement only at higher engine speeds. Under throttled-back conditions,predictions and experimental data deviate considerably, and actually become of oppositesign at the lower engine speeds.
Fuel flow rate, turbine inlet temperature, and turbine outlet temperatureall increased by considerably greater amounts than were predicted by the O.D.P.program (see Figs. 23, 24, and 25). Nevertheless, the experimental influence coeffi-cients confirm the linearity of these responses withasmall changes in main bleed rate.The similarity in discrepancy between predicted and experimental results for the fuelflow rate and the turbine temperatures suggests the effect is real, as compatibility oferrors in two separate measuring systems ti unlikely. From an operational viewpoint,the results indicate that the increase in limiting (turbine inlet) temperature caused bymain bleed air extraction is likely to be more severe than the 0. D. P. program predicts,and hence some conservatism is justified when predicting the maximum permissiblemain bleed extraction rate.
The higher-than-predicted fuel flow and turbine temperature responses arereflected in lower-than-predicted (negative) thrust and specific thrust responses (seeFigs. 26 and 27); i.e., the higher temperatures prevented the thrust from decreasingas much as the O.D. P. program predicted. These two effects counteract one anotherto some extent and yield closer agreement between the experimental and predictedvalues of the specific fuel consumption response as illustrated in Figure 28.
No definitive ex-planation can be offered for those discrepancies betweenanalytical and experimental response; however, the approximations of constant com-ponent efficiencies and constant pressure losses Incorporated in the 0. D. P. programwere undoubtedly contributing faetors.
7.0 COMPUTED AND MEASURED EFFECTS OF INCREASED PROPELLING NOZZLEAREA WITHOUT MAIN BLEED EXTRACTION
As pointed out In Section 6.0, one of the effects of compressor main bleedextraction was an increase in turbine inlet temperature - a major limiting operatingparameter. Reduction of turbine back pressure, achieved by increasing the area ofthe propelling nozzle, reduces this temperature. In order to establish the effects of achange in nozzle area on the major cycle parameters, one test run was conducted withthis area increased by 7.52%, without any main bleed extraction.
The analytical prediction of these effects was obtained from the O.D. P.program, which computes the propelling nozzle area from the continuity relation, byinputting a multiplier to modify the area generated du ringthe calculation of the standard
_4
14 .
sea level design speed cycle. By iterative calculation, the cycle was forced to adjustto this enlarged area for all subsequent full speed and part-throttle conditions. Analyt-ically derived influence coefficients for area increases of 5% and 10% are plotted onFigure 29 to show the slight nonlinearity with nozzle area increase. The measured andpredicted changes in engine parameters and the corresponding influence coefficients(as defined in Section 6.0) are plotted on Figures 30 to 37.
Very good agreement was found between measured and predicted values of
L. P. compressor pressure ratio (Fig. 30) and specific fuel consumption (Fig. 37) overthe useful engine operating range. With all other parameters, the O.D. P. programgreatly overpredicted changes caused by the increased propelling nozzle area, especiallyabove 77% L. P. compressor speed where the anti-surge bleeds are closed. Surprisingly,the computer program produced step changes opposite to those measured on the engineat the point where the anti-surge bleed valvee closed. Because of this peculiarity,botter agreement between experimental and analytical results can be observed at thelower end of the engine speed range. It is interesting to note that in all cases wherediscrepancies exist between measured and computed values, the O.D. P. programpredicted changes greater by a factor of 1.5 to 2.0. Proportionate overestimation offuel flow rate change (Fig. 32) and thrust change (Fig. 35) again yielded close agree-ment between the measured and predicted specific fuel consumption responses (Fig. 37),a case of "two wrongs making a right".
8.0 COMPUTED AND MEASURED EFFECTS OF INCREASED PROPELLING NOZZLEAREA WITH BLEED EXTRACTION
To establish the effects of combined bleed extraction and nozzle area change,one test was run in which the maximum amount of H. P. bleed air was extracted, withthe propelling nozzle area increased by 7.52% relative to the Basic Engine. The bleedflow rate varied from 8.4% to 9.8%, generally increasing with engine speed as shownin Figure 18. This increased flow rate was achieved by further increasing the T-nozzlearea to 20.00 sq. in.
Opening the final nozzle kept the turbine inlet temperature increase within500C at the higher engine speeds. Changes in the major cycle parameters as functionsof L. P. compressor speed have been plotted on Figures 38 to 45. With two interactingdisturbances to the Basic Engine cycle, viz., main bleed extraction and change inpropelling nozzle area, unique influence coefficients were unobtainable as can readilybe noted from the definition of these coefficients in Section 6.0. In addition to reducedexperimental data and the O.D. P. program predictions, a second prediction has beendisplayed in the above Figures. This estimated change comprised the algebraic sum ofthe single-variable influence coefficients for main bleed extraction and propellingnozzle area change, viz.
AAC~AxBV AANOZwhere CJL asud V/A are influence coefficients relating to uompressor main bleed andII II,'
propelling nozzle area increase respectively. A represents any engine parameter
and AA its change.
S.- 1 5 _
Considering the rather unsuccessful attempts at predicting cycle parameterresponses to main bleed extraction and nozzle area change individually, the relativelypoor agreement betwepn measured and predicted parameter changes in the case ofcombined disturbances to the Basic Engine cycle was anticipated. As one would expect,the two analytical curves (O.D.P. program and summation of individual influencecoefficients) are quite similar in all plots. Although the relative agreement, or lack ofit, between experimental results and analytical predictions varies for differentparameters, none is good enough to justify quantitative use of the O.D.P. programrredictions.
The best agreement occurred with the L. P. compressor pressure ratio (atL. P. spool speeds above 77%) and the specific fuel consumption, (see Figs. 38 and 45).The latter agreement again resulted from fortuitous combinations of individual discre-pancies in fuel flow rate and thrust changes (see also Sections 6.0 and 7. 0). Themeasured changes in H. P. compressor pressure ratio, thrust, and specific thrust wereless than the predicted changes by a factor of approximately 2/3, as can be seen onFigures 39, 43, and 44. Responses of the other parameters, fuel flow rate and turbinetemperatures, bore little resemblance to the predicted values. As can be noted fromFigures 40, 41, and, 42, all three of these, variables increased significantly under thecombined effects of bleed extraction and increased nozzle area, whereas the O.D. P.program, forecast slight decreases at high engine speeds and only moderate increasesat low engine speeds. This inability of the O.D. P. program to forecast accuratelychanges in turbine temperatures detracts seriously from its usefulness as a tool forassessing permissible maximum bleed extraction rates.
9. 0 CONCLUSIONS -
Comparisons between actual test results and values predicted by the currentversion of the O.D. P. program led to the following conclusions:
i) The Off-Design-Point program provided very good predictions of majorcycle parameter changes of the Basic Engine under part-throttle operatingconditions.
if) The approximation of linear proportionality between uorrected L. P.compressor speed and corrected air mass flow rate (used in the O.D. P.)underestimated the flow rate by as much as 3% in the 75% to 100% enginespeed range. Below 75% engine speed, the approximation continuouslyoverestimated the air mass flow rate. 4
iii) In general, the computer program with its simplifying approximations wascapable of predicting only within a factor of two, responses of major cycleparameters to H. P. compressor bleed extraction, changes in propellingnozzle area, and combinations of both perturbations.
iv) In particular, the current version of the 0. D. P. calculation routineunderestimated the turbine inlet (and turbine outle*% temperature responsesby a factor of two. This imprecision seriously Aotracts from its useful-ness as a tool for assessing permissible maximum bleed extraction rates,and will be the subject of further analysis.
~ ~ -.. *.~ - -- -
- 16-
10.0 REFERENCES
1. Cockshutt, E. P. Gas Turbine Cycle Calculations: A General Methodfor the Computation of Off-Design Performance.(To be published).
2. Chappell, M.S. Gas Turbine Cycle Calculations: Design-PointCockshutt, E. P. Performance of Turbojet and Turbofan Engines,Sharp, C.R. NRC, DME Aero. Report LR-407, National Research
Council of Canada, October 1964.
3. Cockshutt, E. P. Gas Turbine Cycle Calculations: Differential Methods. in the Analysis of Equilibrium Operation.
NRC, DME Aero. Report LR-481, National ResearchCouncil of Canada, March 1967.
4. Davis, W. R. A Computer Program for the Analysis and Design ofthe Flow in Turbomachinery.Carleton University, Faculty of Engineering, Divisionof Aerothermodynamics Report No. ME/A 69-1,December 1969.
5. Chappell, M. S. Gas Turbine Cycle Calculations: ThermodynamicCockshutt, E. P. Data Tables for Air and Combustion Products.
NRC, DME Aero. Report LR-517, National ResearchCouncil of Canada, January 1969.
6. Chappell, M.S. J-75 Engine Compressor Bleed Air as a Source ofGrabe, W. Rig Turbine Drive Power.Prince, E.J NRC, DME Lab. Tech. Report LTR-ENG-12,
National Research Council of Canada, April 1971.
I'-t
17 4
FIG. I :J- 75 TURBOJET IN No. 4 TEST CELL
-18 -
MAIN BLED EED,;'
EXTRACTION PIPES
FIG. 2 ANTI-SURGE AND MAIN BLEED EXTRACTIONPIPING CONFIGURATION
FiG. 3 PROPELLING NOZZLE AND BLEEDAIR T-NOZZLE
-20-
~1~ME URI Na
I IM
I ORIFCEPLATE
Orr I. Iec INA
afta g C- 24"7 D.-242980 -2499itoy
0-25024
SEC TION' D' 8-241 JimW
r,2405-,'*-25020
ýL-j/ 2-5000
8-25014
II E-25010'
!SErT 0N WV9
CD,
0-25025
-4-F
C-0-25024
--- E-250w" 1 D' ENIN WITH P DOVSIO FO48' 503 ' BLEED AIR EX-TRACTION
~~-~~8-8011REP E.L DW. A-~72 FIGREL
-21-
2ii,0
AU)�14LUK 2'-I-g�4
-I
CDZz2wI-
WILU
z0I-C.)LUCl)
U,
I'
_________ __ A
- 22-
ww
I 2 .CL 00 0
-J_ _ _ _ _ _ _ _-~ 0___I Lu L
- -i
4LLI 4
_ _ _ 000 O0
ZN o/ 033dS lO0dS d*H
90_
0.D0,P. PROGRAM/
G----OEXPERIMENTAL
70
-J
60-
50
/ A/S BPLEED:SOPE CLO SED
40 50 60 70 s0 90 100L.R SPOOL SPEED %/ N,
FIG. 7 PERFORMANCE OF THE BASIC %1-75 ENGINE
AIR MASS FLOW RATE vs LP SPOOL SPEED
- 24 -
4.0
0. D. P. PROGRAM
0-----OEXPERIMENTAL
2,5,
.2.0
A/S BLEEDSOPEN CLSE
10 5 60 70 s0 90 1 00
L.P. SPOOL SPEED % N1
FIG.8a PERFORMANCE OF' THE BASIC J-75 ENGINEL.P COMPRESSOR PRESSURE RATIO vsLA. SPOOL SPEED
-25-
3501
300 ~ ~ 0 0.P.P PROGRAM______
G.----GEXPERIMENTAL
S250LA/S BLEEDS
LAOPEN __ PCLOSED
'200-- _ _
10.
CLl
150
40 50 60 70 80 90 100
L.P SPOOL SPEED % N1
FIG.8b :. PERFORMANCE OF THE BASIC J-75 ENGINEL.P COMPRESSOR TEMPERATURE RISE vs L.R SPOOL SPEED
-26-
1000 0 EXPERIMENTAL POINTS
SSMOOTHED EXPERIMENTAL DATAE EFFIICIENCY COMPUTED FROM. P R ANDAT POINTS ON EXPERIMENTAL DATA
.95 CURVES OF FIGS. $a, AND 8b.-
~90
&850 mm.........
OPE ICOE
70_____
45060 70 s0 90 100
LP SPOOL SPEED %/ N1
FIG. 8c ' PERFORMANCE OF THE BASIC J-75 ENGINEL.P. COMPRESSOR ISENTROPIC EFFICIENCY vs L.P. SPOOL SPEED
-27-
4.0
- O.D,P. PROGRAM
0----GEXPERIMENTAL
23.5
2.5
40 50 60 70 s0 90 100
L.P SPOOL SPEED %/ N1
FIG.9a PERFORMANCE OF THE BASIC J-75 ENGINE-; HAP COMPRESSOR PRESSURE RATIO0 vs L.P. SPOOL SPEED
-28-
350
- O.D.P.- PROGRAM300
0-----0 EXPERIMENTAL
I-200
0 150
3!10
40 5 07 09 0
L.P. SPOOL SPEED /.N,
FIG.9b: PERFORMANCE OF THE BASIC J-75 ENGINEH.P COMPRESSOR TEMPERATURE' RISE vs L.P SPOOL SPEED
-29V-
100
95 - - - _
90C
U.w
85C
w
so
0EXPERIMENTAL POINTS0
U 7 -5SOOHDEPRIETLDTa.:HE XERMNALDT± [EFFICIENCY COMPUTED FROM P R AND &T
POINTS ON EXPERIMENTAL CURVES OF FIGS. 9aAND 9b, TOGETHER WITH L.P, COMPRESSOR
70 TEMPERATURE RISES FROM FIG, 8b.]___________
-0 OD. P. PROGRAM
651I _
40 50 60 70 80 90 100
L.P. SPOOL SPEED 0/0N 1
FIG. 9c :PERFORMANCE OF THE BASIC J-75 ENGINEH.P. COMPRESSOR ISENTROPIC EFFICIENCY vs L.P. SPOOL SPEED
-30-
12 _ _ _ _ _ _ _ _
- O.D.P. PROGRAM
0'----0 EXPERIMENTAL
10-- _ _ _ _
-J
-0004
2-L
40 50 607 o90 100
L.P. SPOOL SPEED %/ N,
FIG. 10a ' PERFORMANCE OF THE BASIC J-75 ENGINEOVERALL COMPRESSOR PRESSURE RATIO vs L.P. SPOOL SPEED
400 -1
350
- O.O.P. PROGRAM
O----OEXPERIMENTAL
300
w 250
I:: - - OPEN [CLOSED
150 IF
40 50 60 70 s0 90 100LP. SPOOL SPEED % N,
FIG. 10b: PERFORMANCE OF THE BASIC J-75 ENGINEOVERALL COMPRESSOR TEMPERATURE RISE vs L.P. SPOOL SPEED
-32 -
1000 0 EXPERIMENTAL POINTS
SMOOTHED EXPERIMENTAL OA*A'[EFFICIENCY COMPUTED FROM PR
95 AND AT, POINTS ON EXCPERIMENTAL95 ~DATA CURVES OF FIGS. 10a AND lot.
mO.D.P. PROGRAM
'90 1
w
A/LBEEDSl
OPEN CLOSED
40 50 so 70 so 90 100
L.P. SPOOL SPEED % N,
FIG.I0c :. PERFORMANCE OF THE BASIC J-75 ENGINEOVERALL COMPRESSOR ISENTROPIC EFFICIENCY vs L.P SPOOL SPEED
- 33-
it ~14 -
2 12 0. D.P. PNOGRAM \
0-t0EXPERIMENTAL
11B4
8. -
w 0LL
A/S B3LfEEDfIOPEN ICLOSED
405 070 s0 90 100
L.P. SPOOL SPEED %o N,
FIG.U : PERFORMANCE OF THE BASIC J-75 ENGINE
FUEL FLOW vsL.P. SPOOL SPEED
A-340.O C 0 '_ P. '0- _A IIt ý6I
O--PQ E IMENJTA (y, DERIVED DATA
000
w
z /1
500 a® - ~
30 4 060 70 80 s0 100
L.P. SPOOL SPEED %N 1
FIG. 12: PERFORMANCE OF THE BASIC J-75 ENGINETURBINE INLET TEMPERATURE vs L.P. SPOOL SPEED
I .. I
- 35 -
900
850 - O,DP. PROGRAM -- /._.'/_ _
"----'-O EXPERIMENTAL
800
-j 6500..
S600
I A/S BLEEDS
550 _OPEN CLOSED
500
30 40 50 60 70 80 90 100
L.P. SPOOL SPEED %Nl
FIG. 13: PERFORMANCE OF THE BASIC J-75 ENGINETURBINE OUTLET TEMPERATURE vs L.P. SPOOL SPEED
- 36 -
9XPERIMCN1AL
o 1.8-
1.4/
00_ OPEN CLOSE.D
1.2 - 9 LLEDt
I ULP. SPOOL SPEED %oNio ro
FIG. 14: PERFORMANCE OF THE BASIC J-75 ENGINEL.P. TURBINE OUTLET PRESSURE [EP.R.] vs L.P. SPOOL SPEED
-37-
ý16 - _ _ _
- ~.DAP PROGOAM
0-OEXPERIMENTAL
ID,
Ice
L.P. ~A/ BLEEDSEE %N-
44
-38-
70
-� .o..P. PROGRAM
6EXPERIMENTAL
to.
30-
U
20- - _ ______ _
I A/S BLEEDOPEN I CLOSED
40 50 60 70 80 90 100
L.R SPOOL SPEED % N1
FIG.15b: PERFORMANCE OF THE BASIC J-75 ENGINE
SPECIFIC THRUST vs L.P SPOOL SPEED
________I.
_______ _______-39- _ _
0.0,P. PROGRAM
(D----O EXPERIMENTAL
-c
m
8..
OOPE
6070809010
LP.~~ SPO APE /S NLE
FIG 16PERORMNCEOFPTEN BSCLOS7ENGN
SPECIFIC FUEL CONSUMPTION vs L.R SPOOL SPEED
El .40-
0
0z
I, _
LUCL
NH Wa.
____qnNO ____j 0I UU
81A
-41-
10
91 - 9.0% AVE, -- NOZZLE ARE
0STD. NOZZLE AREA
3
OPEN 1CLOSED
PERCENTAGE BASED ON ENGINEINTAKE MASS FLOW RATE
0I40 50 60 70 80 90 100
L.P. SPOOL SPEED N
FIG. 18 : BLEED EXTRACTIONMEASURED MAIN BLEED FLOW RATE vs LP. SPOOL SPEED
-42-
3.5
I A/S LEEDS1
-' 5% "mAIN 6L EEO
2.0
uj
L.P. SPOOL SPEED %N
50 60 70 80 1 90 100
* LW PESSURE CoMPRE SOR PREScSURE FRlOI
-0.50 10
FIG. 19 ' BLEED EXTRACTIONJBLEED INFLUENCE COEFFICIENTS vs L.P. SPOOL SPEED
- 43-
40%
3.0 50%%.0/
60% A/S
BLEED70%
85%~
90% ~.A/Sz 95%~
o. 1.0
D 100 -a1
PECNAEMI LE
~~~PERCENTAGE MAIN BLEEDFOVAIUENNESED
- 44 -
LP. SPOOL SPEED %N Ni
___50_____so__ 90 100
.7 0
0.02-0
-~~ 5.3 % -
-03.6%
LA. SPOOL SPEED %N1
Jc50 so 70 so 90 100
0.m~
0.4
FIG. 21 : COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED EXTRACTION
L.P COMPRESSOR PRESSURE RATIO vs L.P. SPOOL SPEED
-45 -
0.10
0 4
~0.0
MESUE LLEE SPOOLSPEETED
0,0--- 3.6%
0----0 5.9% -
.2.0
u:,
ui 1.0-
4%4% A/S 8LEEDS
OP CLOSED
S0.5-SOL PE oN
5060 70 1 90 10
-0.5
FIG. 22 :COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED EXTRACTION
H.P. COMkPRESSOR PRESSURE RATIO vs L.P. SPOOL SPEED
ý11 71- 46 -
.800
600,
It 50
.4_00
L, SOO POL NA.2
OPEN l SE
2.8-
4,
N,
0. .2:COPAIONO MEASURED ANLED PREDICTED EFFCTOF MAN3LEDEXRCTO.UE %LWRT sLP PO PE
-47-
7-~
a:
40-
1070 io 0 0
L.P SPOOL SPEED % N,2.0jF MEASURED BLE PRDCD
T- ___ S.E RDCI
w
w
U.z
ASBL=EEDS.OPEN CLOSED_
45060 70 80 90 10OL.P SPOOL SPEED %. NI
FIG.24 'COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED EXTRACTION
TURBINE INLET TEMPERATURE vs L.P. SPOOL SPEED
70
~Ole
0 /0
0 .0 6 0
L.00 SP O p.. 0D
C W EF E
?.0L
E~ ~ L .p E
TU8ujOUL
-49-
20L. P. SPOOL SPEED %Ng
00 1%7000l
.9 so 9
0.69
0.64
U.
0-0.4-I
Z_-0.46I
2-006.\bI
FIG. 26: COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED EXTRACTION
THRUST ve LP. SPOOL SPEED
0.5 -0
- - -- - ~ 60 I
U50 70 so 90 1 0"-bL.P. SPOOL SPEED %P41
I-
2,-
MEASURED BLEED PREDICTED
~ -30 O---0 3.6%
.3-o 5.9 % -4
0.75 ASBED
*i 0.50 -
0.25-
z 602L 0 70- so 9010Ii.w8 -0.25- L.P. SPOOL SPEED %N1
w -0.50 ' N-J *
- 1.25 -
FIG. 27: COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED EXTRACTION
SPECIFIC THRUST vs L.P. SPOOL SPEED
-51-
0.25-
MEASURED BLEED PREDICTED
-j O--- 3.6%
0.20;0--- 5.9 % -
S0.15
0.e
.~0.10-
So
-0J
0.05
U.
0.
1.0-
L.P. ~ A/ SPOLESEE DS
FIG. 28 'COMPARISON OF MEASURED AND PREDICTED EFFECTS
OF MAIN BLEED EXTRACTION
SPECIFIC FUEL CONSUMPTION vs L.P. SPOOL SPEED
- 52-
1.0
0. 5 cpc
0 _ _ I_ _I
0 -0.5 rC -
z -1.0 __
-1.
-20INCREASE IN PROPELLING _____ ____ _____ _____
FIG. 29: PROPELLING NOZZLE AREA CHANGE
INFLUENCE COEFFICIENTS RESULTING FROM CHANGEIN PROPELLING NOZZLE AREA vs L.P. SPOOL SPEED
-53-
0.15-
2S0.10- .,o,<
0.100
a 0.05- f..,-- p
_j
S50 " 70 so 90 100
0,, 000L.P. SPOOL SPEED %N,
0.05t
AREAMEASURED CANGEA PREDICTED
O---G + 7.5%
110-
I ,
0
o' 50 •.. ' 60 70809I0
z0.- -
L.P. SPOOL SPEED SNI
- ""..!PEN IcLOsED_-0.
FIG. 30" COMPARISON OF MEASURED AND PREDICTED EFFECTSOF CHANGE IN PROPELLING NOZZLE AREA
L.P. COMPRESSOR PRESSURE RATIO v$ L.P. SPOOL SPEED
0r ! 1 1 1
-0.
-54-
0.1
0
LP. SPOOL SPEED /.I'.
0-.060 \70 so 90 100
4I
-02L
AREAMEASURED CHANGE PREDICTED
1.0-
A/S BLEEDS
1-0.5r -NWOPEN CLOSED
wL.P. SPOOL SPEED %/Nl
w50 60 \70 180 90 100
X LL.
-0.5-
FIG. 31: COMPARISON OF MEASURED AND PREDICTED EFFECTSOF CHANGE IN PROPELLING NOZZLE AREA
H. P. COMPRESSOR PRESSURE RATIO vsL.P. SPOOL SPEED
-55 -
LP SPOOL SPEED %N,
0 50 60 70 8o 90 100
-4
MýASURED ARA PREDICTED
A/S BLEEDS
LAP SPOOL SPEED % N,50 60 70 80 90' 100
0
IA.
-2i•,"
FI.2CM PAIO FMASURED ANDA PREDICTED EFET
OF CHANGEINPOELNNOZEAA
FEFLOWRAT sLP SPOOL SPEED %N :
1L04o6 7 o 0,o.0. I1lI
.-.
S• '-o.,• : I .\ \!
z /I
91. I ,
uA.
wI
FIG.32 :COMPARISON OF MEASURED AND PREDICTED EFFECTS '
OF CHANGE IN PROPELLING NOZZLE AREA ."
FUEL FLOW RATE vw L.PR 5POOL SPEED •'
L.P. SPOOL SPEED %N056070 so 90 100
L.P. ~ A/ SPOLEPEDDSN
-s-
MEAURE SPOLSPED % -
-0.2z--o ~ __
FI.3:CMAIONO ESRDAD RDCE FETOF CHNG INPOPLIN.OZL-AE
TUBNUNE EPRTUEv.. PO PE
LP, SPOOL SPEED */.N1
-0- --00
OPEN CLOSED
L.P. SPOOL SPEED %c050 60 70 80, 90 tOO
~,-0.2 4---
I-w
IL
j I AREAILMEASURED CHANCE PREDICTED
0-- -- 0 +7.5 %
FIG.34 COMPARISON OF MEASURED AND PREDICTED EFFECTSOF CHANGE IN PROPELLING NOZZLE AREA
TURBINE OUTLET TEMPERATURE Vs L.P. SPOOL SPEED
-58-
L.P. SPOOL SPEED %N
508000s 90 100
MEASURED AREA PREDICTEDCHANGE
%
L.P. SPOOL SPEED %/r N1
40 % 50 60 70 80 90 100
I-05
2
Lh.
w -0
2.o
-J .5CMAIO O ESRDADPRDCE FETOFCHNG I POPLLNGNOZL AETHUS v LPSPO SED
-59-
L.R SPOOL SPEED %. N,
40 50 60 70 so 90 t00
z 50 MEASURED AREA PREDITEDo2 CHANGE
-60 0--- + +7.5%-zu
L.P. SPOOL SPEED %N40 50 60 70 80 90 100
0
A/S BLEEDSzLa OTPENJ CLOSED~
-0.5-
2 IL
OF1. CHNG INPOELN IOZEAESPCFCTRUTv ASPO PE
- 60-
0*0 (0.091-J0.04 AT 59.1/%)
0.03-
0,02 I
W- 0.01U.I
~ -. 01L.P. SPOOL SPEED
zI-0.02-
~-0.03 I
-0,04- MEASURED AREA PREDICTEDCHANGE
(n LL. 015-
z LL
0 0
LL Zw 0-
ZzA
w
a0.
FIG.37 :COMPARISON OF MEASURED AND PREDICTED EFFECTSOF CHANGE IN PROPELLING NOZZLE AREA
SPECIFIC FUEL CONSUMPTION vsL.P. SPOOL SPEED
-61-
LEGEND:-0-----o- EXPERIMENTAL
~ PREDICTED - OD.P.
-~I-----O- PREDICTED -INFLUENCE COEFFS.
IL.P. SPOOL SPEED IN040 __0 6 0 70 so 90 *100
-0.02-10,
D-0.04-/
-J \o
0O.060
-0.08-
A/S BLEEDF1-0.I0- -PEN_ _CLOSED~
Fir,. 3e CCMPARiSON OF M4EASURED AND PREDICTED EFFECT'SOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
L.P. COMPRESSOR PRESSURE RATIO vs L,P. SPOOL SPEEDMB: 8.4 -9.8 % tAAN : 7.5 %
-62-I
LEGEND:-O- -- c- EXPERIMENTA~L
*.-4 PREDI1CTED -O.D.P.
0.20-D-----~- PREDICTED -INFLUENCE COEFFS.
0.20-
L.fl SPOOL SPEED 0/0N,
50 6070 s0 90 100
LU
w
OP0EN0 CLOSED
-040
FIG. 39 :COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
H.P. COMPRESSOR PRESSURE RATIO vs L.P, SPOOL SPEEDMB :8.4 -9,8 0 6 AN 7.5 %
-63-
600-
400- / 00,
N N
.50 60 70 8 9 looSL., P. SPOOL SPEED
0L. -200-Jw
zLEGEND:"' -400
(9 "<-0----0 EXPERIMENTALzU *•- PREDICTED - O.D,P.
"[---E- PREDICTED - INFLUENCE COEFFS,
-600
A/S BLEEDJS-800 OPEN CLOSED-
-1000
FIG. 40 : COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
FUEL FLOW RATE vs L,P. SPOOL SPEED
MB: 8.4 -9.8%, AAN: 7.5O%
-64-
LEGEND:-0- -- Z-O- EXPERIMENTAL
S-- A PREDICTED " .D.P.
-PREDICTED- INFLUENCE COEFFS.
•,80I
0 40
600 0 7 O
z
0 0
-50 60 70- so-0-1-L.P. SPOOL SPEEL) %/ N,
-20 - A/S BLEEDS
OPEN CLOSED
FIG. 41 COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
TURBINE INLET TEMPERATURE vs L.P. SPOOL SPEED
MB : 8.4 -9.8%, AAN; 7.50/0
• N - • " ' . .. . : :• •:• , • .. . .. "1 ' . .. .. . ... . .. . ... .... .. .j
-65-
LEGEND:-- -- (O- EXPERIMENTAL
SPREDICTED - O.DP.
SPREDICTED - INFLUENCE COEFFS.
80
00
w60 20- - _ .. -
Szo
L - P. SPOOL SPEED %Nl
-200
IA/S 8LEEDS
SOPEN CLOSED
FIG. 42 :COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
TURBINE OUTLET TEMPERATURE vs L.P, SPOOL SPEED
J!MB 8.4 - 9.8 % A AN :7.5 %
|4
-66-
L.PA SPOOL SPEED %NI
40 50 60 70 80 90 1000'
Not.
-500
-I000-
j\
__ " •LEGEND :4 "0-0" EXPERIMENTAL
-2000 PREDICTED - OD.P.-00 ----- - PREDICTED - INFLUENCE COEFFS.
-2500IA/S B•L
.OPEN I CLOSED 0,
-3000
FIG. 43 COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
THRUST vs L,P, SPOOL SPEED
MB: 8.4 - 9.8 %, AAN 7.5 %
-67-
L.P. SPOOL SPEED /.N1
40 50 60 70 s0 90 1000 I
U)
*. . 4 -
I-6
LEGEND,
* ~-0-0-- EXPERIMENTALz
.-. PREDICTED - O.D.P.
z4----D PREDICTED - INFLUENCE COEFFS,
-12
IA/S BLEEDSl
OPEN ICLOSED
-14F-IG, 44 :COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE[ SPECIFIC THRUST vs L.P. SPOOL SPEED
MB 8.4 - 9.8 %/, AAN 7.5 %/
0.40-
LEGEND:
"O---0- EXPERIMFNTAL SPREDICTED-
O.D.P,0.3."- - PREDICTED - INFLUENCE COEFFS,
g-
/ /
_. z 0,30--j 0.5 .OPEN. CLOSED-
w
z020
z
0.105
o cI I 1 <
40 50 60 70 80 90 100
L.R SPOOL SPEED %NI
FIG. 45 : COMPARISON OF MEASURED AND PREDICTED EFFECTSOF MAIN BLEED AND PROPELLING NOZZLE AREA INCREASE
SPECIFIC FUEL CONSUMPTION vs L.P, SPOOL SPEEDMB , 8.4- 9.8 %, AAN * 7,5 %
-69-
APPENDIX A
J-75 DATA REDUCTION PROGRAM:
SAMPLE RAW DATA AND OUTPUT SHEETS
Ii
-I
I.
k •
_____ ___ -71- _ _ _ _ _ _ _ _ _ _
J 75- ENGINE. TES7
Of` 2.41 V7 RUN NO I L) ?JoL W
TE *rP. i 22, lroc.
TIM&. or RXAINC.1 I ,I V 'Y JSI
L P544 'R.? "u.M.bv Avp*qo PAP ISA .6,0_JKr ~Pm.F fT"PRAIU. II '1 7Z9 b!L 47-o 14S11__30
INShIMM OIL POLLSSLOA (/k7I4.) VW%~ tri MLo T)1.0
rut6~ PLOW witNT1 LS/fl 9.1p UV ljr --- aouaa 219MAIN bLEUo UPST. ftD.I. STAiG Paw m+a~ 4 16 ~I
HII P CAMP. MATLILT PPE*BUI11U _plM4 ;22 2766r :V. 74oa % 114, I
IP, COk4PW.ICOSO. O4.TTx LW 6 P.S4 f,79 f- /AL 7I 20. a, 301 .l~ 9-WwtA* St.AAD UPa?, PIN.W. TOYAL. -Pal4h 12.0 19 ____1ýSa k--
a 4. - 17 -d2 V l- 0_l Mo 30
icr ,ipK -rmTx~uw 4 "1 'C .20 229 110: 318 1~ T?~ ...2.
LP~I *OP UIV?*V. - - -0
.%P Cam4p, OU-TLEWT Tamp. -3 IUC 110 -!. - ~ .o Ia.
______________ UD. mc 16 Me 1 /44 201~J ~ l
3LCOIN ~ WtSTD. *a 26 +Z AL 94- 116%.~.J~
MM. Wt4LLID UPST. TU.MPIA'rutaR VC 9j /2 /.4 2l 2-4 J, U -, 20
"Qw %Laub O~CM~.S. TX.#f4. *Q y ( /o-/ __ __~
j _Bi _ _ i5,,ho
EbJ~~W.JI.C -6,0 -4 !.0 42 ~ 7I
A.*S *LgtO pRW.,SuRL P~Or- I~ .iZ/..&,-- Z.2.M~.W I~U~ P.U.b. bP ________ ~i ~LVL _
OILLL O NIR.ATL8VO UP'L 0 Ot 1
rcdIMng fi~kTI blank u~
-72 -
ID"
IaIJ41
0. 00' z
to ca 0cc a,
0~ ~ ~ M 0MQ0j
a. .S 04 O N. W 4 0 U
t 0 0yW o . 00 L6
z w 4 ... ,. t f
6. IL 0.&' S.I cc W PQ~
IL3 %'J we CL "1 5. rl '
- ' j A.~ U.
#0 v~ P. 0 w 3ac 0l t6 ,044 Mo in Ni OU m 2 0It
0 l mw0 0 -. i 4 N 4n 04. 0
1- Nm Na w~w rUwhU4 U%
of u I. P..1
I0.m 0. 0-m 0 X~~~~- a. $Jl. .
APPENDIX B
SAMPLE INPUT AND OUTPUT S3HEETS FROM THE
OFF-DESIGN-POINT (0. D. P.) PERFORMANCE PREDICTION PROGRAM
p-T
"-- .a
-75-
. . i - V mt -oi- P KI'.o"hRA " ~ MU. 00%.
&2 1- a t 4 1, &S1
114s In 4@ WTb. 86! 6 . Jf 0, 1 ,'16 .
1 a- It" I- Ia a JI o ._-
Ibmdl 1 71W~ T14PANI V ~
I Iiz EI-
F _ _ _ *~*.....
I.__ ,iiIiA4 -OZ-
P ICS .1 q
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-76 -
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Nj 430 J, I-
f0 Q 3 3
W N -4 S 45
U a 0 0 o 4 3
3 ~ ~ l Ci W3.1' ~).
Ou 00 U0
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