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N O T I C E THIS DOCUMENT HAS BEEN REPRODUCED FROM MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE
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AVSCOM TR-86-C-15 NASA CR-175110 O " O O
CO M POU ND, CYC L
E N G I NE E R
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HEL
ICOPTE R
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LICATI O N
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MAY 0 ? 1987
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E GARRETT TURBINE ENGINE COMOANY
A&W pf A OIVISION OF THE GARRETT CORPORATION
PHOENIX, ARIZONA
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Nationnal o For; eti Aeronautic: a Space Administration
EXECUTIVE SUMMARY
Center O Cleveland. Ohio Clevend. Ohio 44135
CONTRACT NO. NAS3-24346
21 -5854
Two daemwm to bom ;**T" "&K" am eat: Ir M ar o ml"L All r f i 3, Recipient's Catalog No.
AVSCOM TR-66-C , 15 1 2, &;;m tentAeewsion No.^ OO 1, Report No.
NASA CR-175110 "d 6. Report Data 4. Title and Subtitle 25, i9ais Compound Cycle Engine for Helicopter Application - 6. Performing OrgenitationCode Executive Summary 8. Performing Organization Report No.
7. Author(e) Jere G. Castor 10, Work Unit No.
8, Performing Organization Neme and Address Garrett Turbine Engine Co.
11. Contract or Grant No, 34 Street 111 S.
P.0.8ox 5217 NAS3-24346 Phoenix, AZ 85010 13. Type of Report and Period Covered 12. Sponsoring Awncy Name and Address Contractor Report _ U.S. Army - Aviation Research i Technology Activity - AVSCOM, Propulsion Director&,*, 14, Sponsoring Agency Coda Lewis Research Center 1L16110AFI45 Cleveland, ON 44135-3127 16. Supplementary Notes Program Manager - Propulsion Lirectorate U.S. Army Aviation Research a Technology Activity -AVSCOM Project Manager - William Wintucky NASA Lewis Resear ch Center Cleveland 4413 5 16. Abstract _`" A The Compound Cycle Engine (CCE) is a highly turbocharged, power compounded, ultra- high power density, light-weight diesel engine.
The turbomachinery is similar to a moderate pressure ratio, free power turbine gas turbine engine and the diesel core is high speed and a low compression ratio.
This engine-is considered a potential candidate for future military light helicopter applications.
This executive summary presents cycle thermodynamic (SFC) and engine weight anal- yses performed to establish general engine operating parameters and configuration.
An extensive performance and weight analysis based on a typical two hour helicop- ter (+30 minute reserve) mission determined final conceptual engine design. With this mission, CCE performance was compared to that of a T-800 class gas turbine engine. The CCE had a 31% lower-fuel consumption and resulted in a 16% reduction in engine plus fuel and fuel tank weight.
Design SFC of the CCE is 0.33 lb/HP-HR and installed wet weight is 0.43 ibs/HP.
The major technology development areas required for the CCE are identified and briefly discussed.
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18. Distribution Statement —' 17. Key Words ISuggasted by Authorls)) i Compound Cycle, Diesel, Turbine/Diesel, Light-weight Diesel Unclassified Cidea High Performance Diesel, Helicopter Engine, Low Heat Rejection Engine F ^7iS^ r.}.•f.tal V 22. Pri e' lof 21. No. f Pagan 20. Security Clessif. this p age) 18, Security dassif. (of this report) Unclassified Unclassified i ingfield, Virginia 22161 For sale by the National Technical Information Servi K TO OA now foe MMtsrr w A ; 8 5. 06L, Is P-3310425 oMaan Tura" anon "THM COM PANY A awuow a THE a^[n w11 ► o^1 ► r1oN Po"0419, AMso"
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COMPOUND CYCLE ENGINE FOR HELICOPTER APPLICATION INTRODUC72ON This report is provided as an executive summary of a study funded by the U.S. Army Aviation Systems Command on the subject of compound cycle engines for helicopter appli- cations. This effort, conducted jointly with NASA and under contract with the Garrett Turbine Engine Company ( GTEC), has been underway since mid-1984 ( Reference: Con- tract NA63 - 24346).
A Compound Cycle Engine ( CCE) as shown In Figure i combines the airflow capacity and light - weight features of a gas turbine with the highly efficient but heavier diesel. The com- pressor of the gas turbine module delivers high pressure air to the diesai core where further compression takes place in the cylinders (as with a conventional reciprocating compressor).
Fuel is introduced and burned at very high pressure and temperature, and 'power is extracted in the downrtroke of the diesel piston. The discharge gas, with its remaining energy, then is ducted to turbines that drive the compressor and also augment the output of the diesel core. The term compound cycle,.
Figure 1. Arrangement of Compound therefore, is an expression used to describe Cycle Engine.
the process in which excess power is extracted from the turbomaehinery and compounded power was translated into a small r helicopter through gearing to add to the output of the for the same payload and m mionAl) diesel core.
Earlier estimates, using the Blackhawk Recent studies by the Army have revealed helicopter, showed that the allowable specific that fuel constitutes 70 percent of the tonnage weight of a CCE could be as high as 0.76 lb/hp required to supply and support its forces under and still be competitive with the gas turbine battlefield conditions. Other preliminary because of the large fuel saving. The com- studies by AVSCOM supported by Compound putation was based on the allowable engine Cycle Turbofan Engine ( COTE) information weight increase that would offset fuel and obtained under DARPA / U.S. Air Force Con- tankage weight saved, so that the take-off tract F33657 - 77-C-0391, indicated that a 40 gross weight of the helicopter remained the percent fuel savings potential exists for com- same.(2) pound cycle engine powered helicopters. A 23 percent reduction in required engine power The most fuel - efficient aircraft engine (installed) was also estimated for the same ever flown ( 1952) was the Napier Nomad + mission when compared with a contemporary (3000 hp) compound cycle engine. (3 ) The simple cycle gas turbine. This reduction in Nomad ' s operating conditions were: 21-5854 P-33:0425 n TuM^ NN T co nNr a ► a A OIVINOM OF !Mt OAM!'IT COMOIIAt10M PHNNIM, AMlW1A
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Investigated. A 1 1/2 spool, 2-stroke, uniflow- • Shaft Horse Power -3000+ seavenged CCE with aftercooling** was • Diesel Core Speed -2050 rpm selected on the basis of specific fuel consump- • Compressor Pressure Ratio -6.5s1 tion (SFC-lbs/hp-hr) and engine weight.
• Diesel Inlet Air Temp -475F • Diesel Compression Ratio -8:1 When compared with the contemporary gas • Fuel Injection Pressure -15,000 psi turbine for the 2 hour mission, the CCE offers • Max Firing Pressure - 2200 psi • Brake Mean Effective Pressure -205 psi these payoffs: • Equivalence Ratio -0.65 • Diesel Exhaust Temp. -125OF o 31 percent less fuel consumption o 16 percent less engine and fuel weight • Specific Weight -1.0 lb/hp o 8 percent less engine and fuel volume • BSFC -0.345 lb/hp-hr These values are a result of tradeoff analy- During the 1950's all development effort was ses which showed that large improvements in directed toward gas turbines, hence the engine weight would more than compensate Nomad never reached full scale production, for a slight increase in fuel consumption. The but it represented the pinnacle of diesel air- fallouts translate into the following mission craft engine technology. Applying today's technologies and designs to the Nomad could Improvements: result in an engine having a specific weight o 36 percent more payload or under 0.60 lb/hp.
o 42 percent more range or o One-third more missions for the same fuel Based upon preliminary studies and the significant advancements in technology dem- A recent miss 4n study by AVSCOM showed onstratef unpder the GTEC/Air Force CCTE similar results.% ) program`4P51; the Army undertook a detailed engine analysis for a light helicopter applica- Three major technical development areas tion to establish CCE parameters that would best meet overall program objectives of fuel are identified and discussed. These are: savings and system payoffs.
o Piston ring/liner interface wear life o Exhaust valve life This executive summary presents the ther- o Fuel injection with high heat release com- modynamic cycle analysis, component bustion arrangement, weight, and configuration lay- out. CCE payoffs are compared with a con- There are no technology barriers envi- temporary gas turbine* for a typical 2-hr (+ 30 sioned at this time which should preclude minute reserve) mission. In addition, major successful development of a CCE. 'However, technology development areas are identified and discussed.
**1 1/2 spool - Turbine driven compressor with a SUMMARY bottoming turbine Variants of 2-stroke and 4-stroke turbo- 2-stroke - One power stroke per crankshaft charged and turbocompound engines were revolution Uniflow - Flow from inlet to exhaust in one *Contemporary gas turbine is an advanced design (T-800 class) that employs demon- direction strated state-of-the-art component technolo- Aftercooler - Heat exchanger between com- gies scheduled for production in the early pressor and diesel cylinder 1980's.
21-5854 P-33:0425 QAIMETT TWHMIE MPT C00 ATIOM NY A DIVISION OF TN[ OAMI[TI COIIr011AilON ► MO[NIM, ARIZONA an agressive component technology effort Is nated early, simply because their fuel con- required to achieve the potential payoffs.
sumption and their weights were not competitive. Another general conclusion is HELICOPTER ENGINE CONFIGURATION that 4-stroke diesels 4 and 7 will be much STUDY RESULTS heavier than their 2-stroke counterparts 6 and 9, but their fuel efficiency, although best, was Nine different diesel-turbine combinations, not significantly better than a 2-stroke design.
as shown in Figure 2, were Investigated during A third conclusion is that a 2-stroke, uniflow- the initial screening phase of the study. The scavenged design, 6 and 9,19 much more effi- factors considered in making the selection cient and lighter than a loop-scavenged design, were: 5 and 8. Therefore, the two arrangements numbered 6 and 9 were carried into the next o Specific fuel consumption step of the studies.
o Engine weight o Expected aircraft mission In the final analysis, the choice between 6 and 9 was based on considerations other than The objective was to identify the com- operation at full design power. The added bination that would provide a maximum saving turbine stage in No. 9 provided the needed In mission fuel with the lightest weight engine, flexibility to avoid variable geometry in the so as to achieve a maximum gain In range- turbomachinery or variable ratio gearing to payload for the vehicle. Turbocharged diesels match the speeds of the diesel and turbine (numbers 1, 29 and 3 on Figure 2) were elimi- modules. Therefore, this arrangement, termed 41TIE[IE 2•ST11NE 24TWE LI// NCAE'E101 NNIFLIIN SCANION1 MNl e O O O O ^
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U U 08 p M[ITIIM t[11[[ w[lu IM Mtlll T[G[ILONyII, SPECIFIC WEISNT. LIMP Figure 2. Nine Configurations Design Point (1000 HP) Diesel/Turbine Thermodynamic (SFC) and Weight Analysis.
21-5854 P-33:0425 TIJOF Gi EN I COM 0C TICIN NY a/11METT INC NOA OF TA RM{TT COIIr11MN1RR A DIVINON P"N"I R, ARIZONA ffi a 1 1/2 spool module, offered a better gain in • Diesel core fuel consumption in the 50 percent power • Basic CCE engine range where most of the mission is flown. The • Installation items mission - power profile used to estimate the magnitude of the gains is shown in Figure 3. Previous methods for estimating internal combustion engine core weights were con- sidered inadequate for this study. To develop an approach, five key engine design param- 43.3 bore, stroke, number of cylinders, eters ( 40 12 HOUR MIST ION speed, and maximum firing pressure) were 38.7 + 30 MIN. FUEL RESERVE) Identified and their sensitivities quantified.
Sensitivities were derived by least squares
40 n
regression analysis of data from 21 different turbocharged or supercharged reciprocating
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aircraft engines. All weight estimates for the 16.7 1z^ remaining items were based on data available W from NASA and GTEC.
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The resulting weight equation is shown in Figure S.
0 10 20 30 40 50 50 70 80 90100 ^^^ 11 PERCENT RATED POWER = R MNSOSEI I - T MS T ROKEI & N CYL M RPI0 P P S ( MAXI
V CO RE
/ Time Profile.
Figure 3. Mission Power The resulting comparison of specific fuel consumption as a function of shaft power for arrangements 6 and 8 is shown in Figure 4.
TURM Installed engine weights, as reflected in MACHINERY COMPOUNOING SEAR ) AFTE , O MODULE Figure 2, include: CCE _Q1 Ij "YLINDEN UNIFLOW ENGINE ++ 1 . 0 We JE/D.AFM WC = WD + ZMWgP + 0.10 NPC SEA LEVEL, OF AMBIENT CONMTIONG BONE/STROKE RATIO = IAN EFFECTIVE COMPRESSION MTNI = TAG MEAN PISTON SPEED =5000 FPM GIRT ` 1110114FTEN000LED fAN SEPA RATOR LU BRICATIO N INSTALLED 0.01 •,j CCE `?
♦ 11/e SPOOL COMPOUND ENGINE ♦♦ WI - WC + PLODS WF + 0.11 D) + OM NPT + 2,74 Wo M SINGLE SPOOL COMPOUND ENGINE 0.:0 nRr WD = DIESEL CORE PLUS ACCESSORIES WEIGHT — LB ^ WC = UNINSTALLED COMPOUND ENGINE WENNHT — L° 0.01 W I = INSTALLED COMPOUND ENGINE WEIGHT — LD 0.00 MAX = MAXIMUM CYLINDER PRESSURE — PRIA SIMILE SPOOL P O.SN1 Wg = AIRFLOW — LB/DEC WI = FUEL FLOW — LB/NR 0.01 ^^^•^ Ilk SPOOL E = AFTERCOOLER EFFECTIVENESS 0.:0 0 = MEBEL DISPLACEMENT — CUBIC INCHES T00 SOD 400 ON 000 900 in NPC = COMPOUND TURBINE HORSEPOWER NET SHAFT POWER, NP NP T = TOTAL OUTPUT HORSEPOWER Figure 4. Speeffie Fuel Consumption as a Function of Power. Figure 5. Engine Weight Functions.
21-5854 P-33:0425 QAIMETT TU OF THE E T I C O i COMPANY 6A MI g VINON 01 THE MIITT C011 ► 011ATION A P"WOOK APIRMA SELECTED ENGINE CONFIGURATION mise between overall cycle efficiency and weight.
Parametric design point and off - design trade-offs were conducted to evaluate the Core design parameters are shown in Ta- effects of cycle variants, such as, cylinder ble 1. The rpm and Pmax levels established compression ratio, compressor pressure ratio, were reduced from those demonstrated during aftercooler effectiveness, and pressure drop the CCTE program, primarily to enhance life.
across the cylinder. These trade - offs resulted The design point equivalence ratio * of 0.68 In a 1 1 / 2 spool, aftereooled, two stroke was selected because it is recognized as an uniflow scavenged CCE, with a thermo- dynamic cycle as shown in Figure 6.
Table 1. Diesel Core Description.
An aftercooler was introduced to reduce • Engine RPM cylinder inlet air temperature, so as to reduce • Airflow Rate, lb/see 2.44 combustion, ring-reversal and exhaust valve temperatures. Addition of the aftercooler and • Bore, in. 3.10 Its weight was offset by reduced cylinder size o 2.94 Stroke, In.
and a lighter diesel core because of higher • No. of Cylinders 6 charge air density. More importantly, it will 133.2 • Displacement, in.3 enhance engine life. However, a small SFC Increase ( 0.02 lb/hp-hr) will be incurred. • Equivalence Ratio 0.68 • Peak Firing Pressure, 3362 The best SFC and engine weight balance Pmax Asia was found to exist at high compressor pressure • Effective Compression Ratio 7.5 ratios ( over 10). The diesel core effective compression ratio was limited to 7.5 in order • BMHP, psi 293 to keep peak firing pressure below 3400 psia.
A diesel flow pressure drop of 10 percent Actual Fuel/Air Ratio = across the cylinder achieved the best compro- * Equivalence Ratio / Stoich Fuel Air Ratio DIESEL HP = 750 FUEL TURBINE HP = 241 150 PFI TOTAL HP = 1000 LOAD s FAN EFF. Cr = 75 51 NP DIESEL CORE SSS NP s T 0 = 0.646 153 PSI 1754E NP 14.7 PSI 577F 135 Pal DIESEL + GEARBOX Pal MF LOSSES 1227F = 0.70 58 NP 156 Pal 1 7 (^ 1523 HPI T = 0.845 14.7 PSI OFC 2.44 L6/SEC 6RAYTON LOSSES 11 NP Figure 6. Sea Level, Standard Day, Design Point Operating Conditions of Selected i/1/2 Spool Compound Cycle Engine.
21-5854 P-33:0425 OAIINETT TURSINE ENGINE COMPANY IM A DIVItION 01 TNt GAMBIT CORPORATION PWKWIM, ANIONA industry-accepted value for nonvisible smoke. shp at sea level standard day so that it could A six cylinder configuration was chosen for produce the same 1000 horsepower at 4000 simplicity. feet, 95F.
A conceptual design layout of the selected Flat rating of the CCE on the other hand, CCE is shown in Figure 7. The figure shows Is accomplished by increasing the turbocom- pressor spool speed 4.0 percent and increasing two major modules, i.e., turbomaehinery and diesel core. The turbomachinery module Is the trapped equivalence ratio from 0.68 to similar to the more familiar turboshaft engine. 0.80 for the short duration, rated power condi- It has a typical gas generator spool with a two tions.
stage backward curved, broad range, high pressure ratio centrifugal compressor, driven The results of the mission comparison by a single-stage, radial-inflow turbine. The study are shown in Table 2. Total fuel, tank, half-spool axial power turbine is geared into and engine weights have been calculated under the compounding gearbox. The turbo- static operating conditions for a twin engine machinery is mounted into the V-form of the application. These results show a potential diesel core so as to minimize overall box for: volumes to less than 14 cubic feet, including oil cooler and aftercooler. The two-stroke o 31.4 percent savings in fuel consumption diesel module has six cylinders, is uniflow o 15.8 percent savings in engine plus fuel scavenged, and has four exhaust valves per weight cylinder, which are activiated with overhead cams. Fuel injectors are located centrally in o 8.5 percent savings in engine plus fuel the cylinder heads. A low heat loss combus- volume tion chamber with thermally isolated and pre- ferentially cooled cylinder liner/head and for a given o One-third gore missions piston dome are used. The engine is oil cooled quantity of fuel and fully self contained with all engine required-to-run controls and accessories. These savings may also be translated into Total installed weight including oil, oil cooler, more range or more payload for the same fan, and inlet air particle separator is 432 lbs gross weight vehicles: for a specific weight of 0.43 lb/hp.
o 36.5 percent increase in payload or o 40.7 percent increase in range MISSION COMPARISON 1111TH GAS TURBINES The CCE configuration selected for this ALTITUDE PERFORMANCE study resulted from an analysis of many engine design and performance parameters to mini- Shaft horsepower and SFC as a function of mize the sum of engine plus fuel weight for altitude, for the selected CCE, are shown in the mission. This engine meets the major Figure 8 for hot, standard and cold day condi- tions. Flat rating at 1000 shp for the verious study objectives of at least a 30 percent savings in fuel. conditions is achieved by allowing the equi- valence ratio to increase to a value of 0.80.
The mission used in preliminary design is This condition is reached at 4,000, 7,000, and the Army's standard of 2 hours plus 30 minutes 9 9 600 feet for hot, standard and cold days, fuel reserve and is typical for a twin-engine respectively. The cold day SFC curve below light helicopter. The mission is flown at 4000 99600 feet is affected by changes in fuel injection timing and trapped air equivalence feet on a 95F day, and the engine is designed to be flat-rated at 1000 shp to the hot day/ ratio. On a standard day, engine operation at altitude conditions. For comparison, the 0 0.68 is about equal to the hot day perfor- simple cycle gas turbine was sized for 1400 mance at A 0.80.
21-5854 P-33:0421 0AMETT TtmaMra eNOM ca ► Nr avIaoN or rNt oAMt rr car ► oRAraN A POOSMIM, ARIZONA TURBOMACHINERY uwwus M. %.
I&M-11 Figure T. Conceptual Design of 11/2 Spool Compound Cycle Engine.
Table 2. CCE/Gas Turbine Consumption and Weight Comparison At 4000 Peet 95F Day.
Contemporary CCE On Turbine Percent Time ME Fuel e Power (hours) (lbf hr) (lbs) (lbAwhr) (ON) 100 0.08 0.342 28.6 0.457 38.1 75 0.42 0.349 109.2 153.5 0.490 50 1611.5 0.58 0.377 110.0 0.553 0.92 0.400 146.7 0.603 221.4 50 (reserve) 0.50 0.377 94.3 0.553 138.5 Totals `2.50 **488.7 712.8 Fuel 712.8 488.7 Fuel Tank height 83.0 121.1 Installed Engine Weight 432.4 358.0 Totals Fuel, Tank, and Engine 1191.9 $1004.1 For Two Engines 2383.9 2008.3 CCE Total Welaht *Percent Weight Savings: 1.0 - = 15.8 Gas Turbine Weight **Percent Fuel Savings 1.0 - CCE Total Fuel** = 31.4 Cas Turbine Fuel 21-5854 P- 330 421 ► a ► Msn Tu^ aNOiws ear Nr Aaw^aT"toAiwrrA1aN life limiting factor of most concern is the wear rate of the piston ring / liner interface .0060 matsrUs. Factors which influence wear are: • Piston velocity and engine speed • Piston ring/liner geometries • Surface topography • Material chemistry and properties • Oil film type and thickness --- W Mr I#$ UN • Operating pressures and temperatures — 610" MY • Contamination - foreign and self generated —au Mr • Lubriennt type and additives ^^^ `.` I • p UwUM 1AT4 1M • Time between oil changes Complex interactions between the differ- ent factors make it difficult to quantify over- all effects on engine life. The qualitative effects are, however, well understood. A great deal of experience is available on low power density diesel engines but it is quite AL"M R limited in its extension into the design region@ of the CCE discussed here. Total system Figure IL SHP and BSFC Performance of (single cylinder) testing under controlled CCE Versus Altitude, environment conditions using best lubricant formulations and tribological couples is neces- MAJOR TECHNOLOGY DEVELOPMENT sary to establish a technology baseline for AREAS CCE wear-life predictions.
The turbomachinery module consists of Exhaust Valve Life state - of-the - art technology components. The diesel core configuration follows somewhat The exhaust valve life is the second most conventional design practices for two stroke - Important item for CCE development.
engines, but the cycle pressure, temperatures Exhaust gas valve temperature at full power and speeds are somewhat higher and therefore on a hot day is several hundred degrees hotter beyond today's demonstrated diesel engine than current engines. High temperature creep technologies. and fatigue resistant materials that also have high oxidation corrosion resistance will be Three major technology development areas required. Means to thermally isolate, insulate, have been indentified for the diesel core.
and preferentially cool the valves and seats They are in order of considered importance: will be required.
o Piston ring / liner interface wear life Peel Iniection/Combustion o Exhaust valve life Fuel inj ection with high heat release com- bustion is considered to be the third area for o Fuel injection with high heat release com- development. The primary requirement for bustion the fuel injection equipment for a direct- Injected diesel is to distribute a uniform, Piston 8itff/Liner Interface bear Life finely atomized charge of fuel throughout the Because a main objective is long engine combustion chamber, at the right time and in life, the number one development challenge or the right quantity. If not, excessive peak 21-5854 P-33:0455 GANOTT TUPOMlt aNOVA COMPANY it DOW" OF rot GAMBIT CGMMIM" P"010" N ' NNN U cylinder pressure could occur, exhaust smoke weight. It should be noted, again, that the would increase, and engine life could be shor- CCTE engine was run at 8000 rpm under the tened. High speed requires high injection AF/DARPA program and that the targeted pressures for increased heat release rate com- speed for the CCE is well under that value.
bustion. A high pressure (>20,000 psi) CONCLUSION electronically controlled hydromeehanical type fuel injection system is considered the prime Based on the standard two-hour design candidate.
for minion helicopters, the compound cycle engine offers significant payoffs when com- MISSION PAYOFF SENSITIVITT pared with a comtemporary gas turbine: Figure 9 shows the percent improvements o 31 percent less fuel consumption over a contemporary gas turbine in engine SFC o 36 percent more payload (or 42 percent (mission fuel weight), and range or payload as more range) a funcion of diesel core speed. diesel core As o One-third more minions per unit fuel rpm is increased, the required technology levels in the three major development areas For longer missions, the CCE payoffs are also increased for the improved perfor- increase, consistent with the saving in fuel mance.
consumption.
RECOMMENDATIONS G11101T RMl 1011MTI 1101116 MMIMMMIT Because the payoffs are so significant, it is recommended that the following activities be pursued vigorously: o Piston RIM&iner interface bear Life Expand lubricant formulation, advance tri- «n bology and uniflow scavenged single cylinder R&D activities currently underway on the KUL IM11,1/11 ADEPT program.
o Exhaust Valve Life Demonstrate high power density, uniflow "WOMB to G ► nenGlm w T1II11t scavenged performance and evaluate alternate valving schemes.
Figeure 9. Potential Improvements as a Pwiction of Diesel Bnglne Speed.
o Fuel Iniection/Combustion An engine based upon application of cur- Expand the fuel injector/combustion effort rent technologies could provide a 20 percent started under CCTE on electronically- saving in mission fuel; however, its weight controlled, hydromeehanical injectors.
would be unacceptable. Near-term (moderate) development could produce 25 percent fuel o Overall CCE savings at an acceptable engine weight, but with no gain in range or payload. With an To demonstrate the .overall viability of the agrenive concentrated thrust, however, the diesel core, tests should be performed on a selected CCE offers a 31.4 percent saving in multi-cylinder engine/rig to confirm inte- fuel and about a 40 percent improvement in gration of technologies, core performance, and range or payload for the same vehicle gross life and weight prediction methodologies.
21-5854 P-430425 eruMtntoes MTVCO M eae^r ► Nr rrcaroUraM A pVINOMOr i1N GAIIM RElER6NCM 1. AIAA-84-1393 "An Overview of NASA 4. AIAA-81-1714 "Advanced Cruise Missile Propulsion Concepts" J. Lueke and R.
Intermittent Combustion Engine Research" Spencer.
E.A. Willis and W.T. Wintucky.
5. AIAA-83-1338 "Compound Cycle Turbofan 9. SAE820432 "Preliminary Survey of Possible Engine" J.G. Castor, et al.
Use Of The Compound Adiabatic Diesel "Aircraft Preliminary 6. AIAA-85-1276 Engine For Helicopters" H. Dean Witsted.
Design Comparison Of Advanced Com- pound Engines with Advanced Turbine 3. SAE Transaction Volume 63 1965 "Napier Engines For Helicopter Applleationet W.L.
Nomad Aircraft Diesel Engine" H.
Andre.
Sammons, E. Chatterton.
Z1-5854