Fuel conservative aircraft engine technology

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T i I 1 r u ►

NASA TECHNICAL

NASA W78962 ICAL

MEMORANDUM

N7E-27127 FIEL CONSERVATIVE AIRCRAFT (NASA-TM-79962) 00 39 F HC 403 /MF A01 FNGINE TECHNOLOGY (NASA) r CSCL 211 Onclas G'•/0' 25213

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N Q Z FUEL CONSERVATIVE AIRCRAFT ENGINE TECHNOLOGY i)y Donald L, Nored Lewis Research Cv±!cer Cleveland, Ohio 44135 TECHNI IA L PA PET. to be presented at the Eleventh Congr? - 'if the International Council of Aeronauticai Scj., ^es P sponsored by the American Institute of Aeronautics and Astronautics Lisbon, Portugal, September 10-16, 1978

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sEDWOM ,aa ,r . a mmmmobamasa>•aasrrairsaM 4 11if t:!1. CONSF.RVAT?VC AIRCRAFT ENGINE. TYCHNOLOGY Donald L. Noted Aeronautics and Space Administration National Lewis Ieaearch Center

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Clevelr 3, Ohio 44175 nomics Abstract Aerod Energy Efficient Transport Laminer Flow Control A major new thrust in NASA's seronauti.al Ai r craft Structures research Is the Aircraft Energy Efficiency Program Composite Components and Primary rhlm program, initiated In an effort to minimize Structures the adverse impact of the world vide fuel crisis on hall the aviation industry, will develop technology for Within NASA, Langley Research Center more fuel-efficient subsonic transport aircraft.

responsibility for the three aircraft-related It includes three major propulsion projects: (1) projects while Lewis Research Center manages tloe Engine Component Improvement - directed at current three propulsion projects. The r.•mainder of this engines, (2) Energv Efficient Engine - directed at paper describes three propulsion projects along new turbofan engines, and (3) Advanced Turboprops - with some recent results.

directed at technology for advanced turboprop- powered sircr.ft. This paper reviews each project, E ngine Component Improvement describes s one of the technologies and recent ac- compliahments, and summarizes their respective The CF6 aircraft engine manufactured by the status.

General Electric Company and the JTBD and JT9D engines manufactured by the Pratt L Whitney Air- Introduction craft Group (fig. 2) power the majority of the com- mercial jet fleet. They are expected to do so Following the world fuel crisis in 1973, pre- throughout the 1980s. For this reason, there is a cipitated by the OPEC oil embargo, aviation fuel strong interest in reducing the fuel consumption of prices rapidl eaf_alatcQ, Figure 1 illustrates these engines, and it Is toward his end that the this point. 0 From 197! to 1975. fuel prices Engine C.:mponent Improvement (!CI) project is di- essentially tripled. As a result, fuel coat became rectad.

P a much larger percentage of airplane direct oper- Fuel savings can be achieved through both im- ating cost (DOC:). Taking the Boeing 727 as an ex- a proved engine performance plus imprived performance ample, fuel coat in 1975 amounted to 25 percent of retention. Thus, the ECI project is divided into DOC. by 1975 it had risen to M percent. For air- two subprojects: (1) Performance Improvement and lines to remain economically iable under such (2) Engine Diagnostics. The objective of the Per- circumstances, reduced fuel consumption became a formance Improvement part of the project is to primary objective.

develop fuel saving component technology in the Projections for the future indicate that fuel next few years so that the engine manufacturers can will remain the most important element of aircraft plan for certification and introduction by 1980- operating cost. (2) This element could become even 1982 into the JT81), JT91), and CF6 engines. Com- Larger if fuel prices continue to increase at a ponents could be introduced either on new produc- rate faster than labor costa or inflation. Such tion engines or through retrofit. depending on the escalation seems likely in view of the projected economics. The Engine Diagnostics part is directed increases In air travel which are directly opposed at ide-ntifying, quantifying, and understanding tare to our dwindling supplies of petroleum - a finite performance degradation that occurs with operation- natural resource. Indeed, fuel conservation in al use of the CF6 and JT9D high-bypass-ratio en- itself may become a primary consideration in the gines. When such data are obtained, it will be future. Although future fuel usage Is uncertain, used to establish deaign, operational, or mainte- conservative projections indicate more than a nance criteria for these engine. - or future ad- doubling of the fuel required for air transporta- vanced engines • that would economically minimize tion by the year 2000.(]) the rate of deterioration throughout engine life.

In response to the growing importance of fuel Per formance Improvement efficiency, from the standpoint of fuel conserva- tion as well as the impact on commerc i al aircraft In Performance Improvement, NASA is supporting operating economics, the Aircraft Energy Efficiency and participatiml with both General Electric and (ACEE) program was formulated and implemented in Pratt 6 Whitney in the evaluation, selection, and 1976 by the National Aeronautics and Space Admini- technology deve'.opment of a number of engine: com- stration (NASA). file program represents an ag- ponent improver,ents. The general approach was to gressive, focused approach to the development of first have an industr y team conduct an extensive technology for more fuel-efficient aircraft for commercial airline use. Six major technology pro- feaaibility, technical, and economic analysis of jects constitute the program. By disciplinary component improvement concepts. moth usneral Elec- tric and Pratt 6 Whitney were assisted by Boeing area, they are and Douglas, representing U.S. domestic operators Propulsion of the engines. iWA was also used by Pratt 6 Engine Component Improvement Whitney to perform analyses involving fleet model- Energy Efficient Engine ing, route structures, and airline economics (such Advanced Turboprop analyses were performed by Boeing and nougl a for the General Electric team). Eastern Airlines and Pon American World Airwave also served as consult-

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,, ^^`+^ 4 ^ as f' at size. It should be noted that a low con- onto to NANA to provide independent c.snments on the cepts, which were screened out or not selected by meeits of the concepts, particularly In the main- 1 t.• nance NASA, did have higher fuel savings (e.g., lung duct and retrofit areas.

mixed flow nacelles, incrvased tan diameter). How- 'rhe feasibility analysis was started with a ever, such concepts did not nu-et the economic cri- cwtceptuoI/preliminary design by each engine manu- teria.

facturer for a number of promising concepts. These 71.e fuel ravings shown on figure 4 represent concepts were based on improvements in areas such it measurable, worthwhile, and desirable gain as component aerodynamics, fluwpath ovals, blade to the airlines. In 1976, U.S. domestic trunks tip clearance control, turb,ne cooling affvctive- used 26.6 billion liters (7043 million gallons) of ness, materials and coatings, duct/nozzle/nacelle fuel. (4 ) At an average price of 89/liter (about aerodynamics, forced exhaust mixers, and controls.

'rhe Initial list of concepts (over hO at General 30c/gal) the cost for fuel was over 2 billion dollars. Fuel savings of one percent would have Electric and over 100 at Pratt 6 Whitne y ) were sub- provided a cost savings of over 21 million dollars, Jected to a preliminary screening based on qualita- all amount equal to approximately 8 percent of ._he tive engineering judgment. Concepts deemed to have total after-tax income of the l'^S S domestic air- a small fuel swing potential, high development risk, or various practical limitations were elim- lines in teat same lime period. 5 (And, In 1975, a year of losses for the airlines, this amxn,nt inated.

would have cut their losses In half.)

Following the concept definition and initial screening, a detailed evaluation procedure was used Based on Lite results of th, feasibility analy- sis, the selected concepts are now entering a pro- to simulate the decision-making process that nor- gram of rig testing, engine ground testing, and mally occurs wlien etgine and airplane manufacturers engine flight testing in order to develop their offer new concepts or improvements to airline oper- technology and verity their real potential for ators. A general flow chart for Lite procedure is cotr^onent improvement. Preliminary results are shown in figure 3. For each rema?ring concept ; S',.e premising, and It appears early incorporation of impact on engine price, maintenanc, cost, perfor- these concepts into new production engines, or by mance (thrust and specific fuel consumption), retrofit, will be achieved.

weight, and noise was established. 11.ese data were then provided to Boeing and Douglas to enable them Engine Diagnostics to evaluate similar effects on their respective airplanes. Various operational assumptions (fleet The Engine Diagnostics activity is directed models, route structures, mission profiles, engine toward investigating performance deteriorat.on of usage rates) were also input to permit cunwlative the CFb and JT9D high-bypass-ratio engines. Dete- fuel savings for each concept to be estimated. The rioration occurs in service with these engines as next step was evaluation of the economic impact of illustrated in figure 5. During initial operation, each concept. Varioub economic ground rules (use- oil rapid performance degradation order of l to ful engine life, airline capital Investment hurdle 2 percent in SFC occurs. This is called "short rates, airline tax and depreciation structures, term deterioration." Such degradation occurs on market projections, and fuel prices) had to be es- the first flight or flights of the slrcraft as the tablished to permit calculation of Incrementa l di- engine structure responds to the flight environ- rect operating costs (DOC), return on investment ment, permitting tip rubs and seal wear, hence in- (ROI), and airline payback periods (tl.e time re- creasing operating clearances. In the longer term.

quired by an airline to recover Its full investment other types of deterioration occur, such as ero- cost). Finally, a ranking was made, with final sion, warpage of parts, or foreign object damage, selection by NASA, based on fuel savings, economic which cause another loss of 2 to 3 p.-rcent in SFC.

benefits (a concept required a minimum of 15 per- Partial restoration of Neese losses is achieved as cent after-tax ROI or a payback period of no more the engine is overhauled. lit however, than 5 to h years to be acceptable to Lite airlines), there is an increasing degradati n in performance production potential, retrofit potential, develop- which is , lied "long-term deterioration."

ment risk, development time, and cost to NASA to develop.

Our general approach in this area is to: The above evaluation has led to identification (1) Gather existing flight data, ground test of 17 high-payoff concepts for potential NASA sup- data, and used parts information to establish port. Three concepts were identified for the JT8D, historical trends.

five concepts for the JT9D, and seven concepts for (2) Augment available data with new data from the CF6. In addition, two concepts which are both in-service engines, both from in-flight trending engine and aircraft related were identified by and from ground tests.

Douglas. All concepts hdd acceptable payback pe- riods, and, in most cases, offered a high degree of (3) Assess causes of short-term performance retrofit potential as well as being applicable to degradation thro.;,,h systematic testing of new or new production engines.

low-time engines.

The concepts are listed in figure 4. Also (4) Assess causes of long-term degradation by listed are the reductions in specific fuel consump- collecting in-service trend data on high-'.Ime en- tion (SFC) at cruise and estimates of the total gines and through systematic ground tests of the fuel savings which would be accrued if each concept same engine (both before and after refurbishment was incorporated into new production, or retro- or periodic repair).

fitted, as soon as possible. These projections in- (5) Determine sensitivity and effects of de- volve assumptions of a 15-year new-engine life, teriorated parts on performance of specific com- production through 1990, various degrees of retro- ponents.

fit (depending on the respective concept and en- gine model), and - most importantly - projected (6) Establish statistical trends, analytical :,,V OW I

s 1 i 1 at the conditions corresponding to points In the models, and design criteria, with assncitted corre- tructur- lation of the impact it maintenance practices on flight profile. A NASrRAN finite element n SFC losses, and provile• recomittrndations for both at model, jointly developed by Pratt 6 Whitney and t current and luturs engines. Boeing, is then used to calculate engine deflec- tions due to the external loads - e.g., serodynoml.

Again, NAiA Is supported and participating loads (inlet lift), maneuver loads, and thrust.

with both General Electric and Pratt & Whitney in Figure 6 shows the NASIRAN model. Local interfer- this actitity. Historical performance data and ences resulting from the engine deflections (plus trends from airlines, based on in-flight measure- abradabillty and wear factors) then establish the ments as well as test stand calibrations, will be new clearance. I.or.- in component pt-formance 16 analyzed. Tit,- effect of specific repait's will be co.culated frsan the average clearance increase, determined based on pre- and post-repair test data.

and this result is used to calculate loss in SFC.

Also, the condition of specific parts will be ex- Figure 7 compares predicted performance amined to determine wear and clearance changes with elms, cycles of use, and performance levels, nits of flight cycles against ac- losses as a function historical data will be augmented b^ • new, specific tual data -in short - term deterioration. In this data from current in-service engines. For example, case, the model was used to predict effect of mint- new JT90 engines on the I l an American 74751' air- mum and traximum build clearance• on performance de- terior..tion. Most of the actual data tells within craft will he monitored, both in-flight as well as through engine tests run while the aircraft is on the predicted band with the average data line ahow- Ing the same increase in SFC with flight cycles as the ground, to attempt to obtain more data on en- does the NASTRAN data.

gine deterioration.

Another indication of the accuracy of this Specialized back-to-back testing will also be accomplished, using both low-time and hLgh-time model is shown In figure 8. Fan rub patterns for engines. Systematic module replacements between a Pan-American engine on the Boeing 747SP after old and new engines and subsequent performance 141 flights, and for a 747 certification engine, testing will be performed by General Electric. after 150 flights, are compared to the NASTRAN cor- Pratt 6 Whitney will apply simulated aerodynamic predicted fan rub wear after 150 flights. 7'he • loads to the JT9D nacelle and monitor the engine relation Is quite good. It should be mentioned that patterns for other components did not corre- running clearances by X-ray techniques. Within late as well, although in all cases there was still modules, sensitivity of components to wear and erosion will be determined b y both companl,!s a good correlation between the average actual wear through back-to-back tests and measurements. and the average of the predicted wear (i.e., total Underlying this entire effort will be a continuing area increase was correlated).

analytical activity to understand the data, ;o e • s- The schedule for the ECI project Is shown in tabllsh analytical models for prediction of dete- figure 9. In the Performance Improvement area, rioration, to evaluate the impact of maintenance feasibility analyses have been completes and con- procedures, and to establish design criteria for cept technology development is now underway. Hn- future JT9D and CF(3 engine models so well as newer gine diagnostics Is very active, with r. number of engines of the future.

tests underway. Component sensitivity tests are fn To date, the Engine Diagnostics activity has the planning stage. Short-term deterioration teats concentrated primarily on data-gstherLng. Analysis of a JT9D engine under simulated flight loading of the large a.nount of data is still somewhat ten- conditions, in Pratt 6 Whitney's X-ray test tacil- tative and inconclusive. "rhe historical data, as Lty, are also being defined.

might he expected, are limited in their suitability for assessment of the specific causes of deteriora- Energy Efficient Engine tion, but they are useful for establishing trends, effect of cycles versus hours of operation, and The second ACKF propulsion effort, the Fnergy differences in engine deterioration between opera- Efficient Engine (E ) project, involves developing and demo.:istrating the technology base for achieving tors because of maintenance and repair practices.

higher thermodynamic and pr-tpulsive efficiencies 'n Ccxn,)onent performance losses (and potential for future commercial turbofan engines. Specifically, recovery) versus usageare still being evaluated, and final models and design criteria will be devel- the project is aimed at achieving technology read- oped as the controlled specialized back-to-back iness by 1983 in the areas of advanced components tests augment the historical data. and systems. At that time, such technology could to selected by an engine manufacturer for incorpor- one example of progress in this area, however, ation into a new or derivative engine development is the development of an analytical procedure by program with an acceptable degree of risk. Deriva- Pratt h Whitney for predicting the effect of flight tive engines could thus appear on the market in loads on short-term performance deterioration. As the mid-tc-late 1980s, or in new turbofan engines mentioned earlier, it is believed the primary cause by the late 1980s or early 1990s depending on the of early, rapid deterioration is the increase In technology evolving airline market needs. E 3 core operating clearances due to seal wear. Me analyt- could also be used in future advanced turboprop ical procedure that has been developed investigates propulsion systems.

this effect. The damage taechanism considered was NASA has recognized that future new engines the increase in local clearances caused by relative must not only be fuel-efficient but also must be wear of rotating blade tips and s-alionary seals.

economically attractive to the airlines its well as Such wear, or interference, is considered to he being environmentally acceptable. For these rea- caused by loads imposed through engine deflections resulting from flight loadr j"F ecting the engine- sons, NASA established a set of goals to provide nacelle-pylon strucutre. the procedure starts with guidance for engine cycle and concept selections a flight profile description and a definition of and for subsequent development of E component and maximum flight loads, as developed by Boeing. systems technology. 'Riese goals are: Pratt 6 Whitney then develops baseline clearances Mall timilli^l,

W when both U.S. domestic and International missions (1) There should be a significant performance improvement over curre nt were considered. Typically, however, there was al- high-bypass-ratio engines.

ways a Ilt)C penalty for the grared versus direct- Speclflrally there should be (a) at least a 12 per- drive engine case. Also, at was believed that cent Improvement in SFC accompanied by (b) at least the high degree of mechanical complexity of a a 5 perce p t improvement In IKX along with (c) at (a) grarrd rn g ine (e.g., in addition to the gearbox, least 50 percent lower deterioration rates than ex- nxor • main bearings were required), coupled with prrivnced by current engines.

(b) the relatively unknown and unpredictable dura- (2) There should be no degradation in en- bility and reliabilit y of a lightweight, high-power vironmental quality. Anv new engines of the late gearbox uruler flight load cem.iltions, would require 1980* or early 1990s must meet note* and emission a very extensive and expensive commercial develop- standards that might by In torte at that time.

ment program to substantiate gearing durability for Currently, of course, the miniaxmt standards are ► a a future commercial energ y efficient engine. Tt the FAR-36 noise requ i rements (as amended March impact of the large performance sensitivities, 1977) and the 9PA eir.salon standards for engines giving marginal or no bvii0its under n oxtK • circum- mortified after January 1981.

stances, along with the mechanical uncertainties which could affect future cumtercial accvptabillty, (i) There should be a thrust growth capability led to selection of the• direct-drive engine config- in the E 3 technology that reflects (a) the uncer- uration for the E 3 program.

tainty as to thrust size of any future engine based on E technology and (b) the realization that com- A wide variety of engine -ycl y & were assessed mercial engine modela will undergo a wide range of In tilt- engine definition studies. The selected ► .d downratings. Such grwth thrust upratings a cycles are ahown in figure 10 In comparison to the capability must he accomplished without compro- current production engines used as reterence en- mising the other goals.

gines in estimating performance improvements of the E ) design. Improvements in all areas were realized, To arrive at engine designs to meet these leading to the desired improvements in thermody- goals, NASA awarded engine definition contracts to namic and propulsive efficiencies, (lie cycle con- both domestic manufacturers of large conmereial ditions as r,hown in figure 10 art . based on exten- :orbuf n engines (General Electric and Pratt 6 sive optimization and tradeoff studies of the ef- Whitney). Candidate engine configurations and fect on fuel burned and IOC when varying parameters cycle conditions were selected by each contractor such as overall pressure ratio, turbine inlet tem- ) extensive refinement and tradeoff studies.

li m perature, and b y path ratio. The cycles selected Assistance was provided by Boeing, Douglas, o are not Elie optimum trom the standpoint of fuel and Lo, kneed in evaluating the impact on thrust efficiency slor ► e. It was recognized that vngine levels, cycle conditions, and engine configuration first cost, life. and maintenance cost must be due to integration with possible future aircraft traded off against fuel efficiency, while also pro- designs. Pan American World Airways and Eastern viding for a reaiistic growth margin if a cost ef- Airlines also provide independent evaluations of fective airline acceptable design is to be the the engine conllgurationr.

final result.

con- Four basic types of turbofan engines were • Associated with the engine cycles are advance- sidered in these studies: ments and improved efficiencies in every component.

Direct-drive fan with a separate core and (1) While the selected engine design of cacti engine, fan stream exhaust manufacturer was the same (two-spool, direct-o:rive, mixed-11,w exhaust), each tied different approaches (2) Direct-drive fan with mixed core alit: fan to component design, reflectAns his own level of stream exhaust (lone, duct nacelle) component technology. Figure 11 illustrates the (3) Geared fan with separate-flow exhaust engine design configuration of g eneral Electric.

Some of the major advanced technology features are (4) Geared fan with mixed-flow exhaust (long also indicated on the figure.

duct nacelle).

The fan is an advanced aerodynamic design with (loth engine manufacturers selected the direct- mid-span dampers located near the trailing edge of drive, mixed-flow engine configuration.

the titanium blades. A tan hub quarter-stage Mixers clearly provided advantages in SFC, booster is used to permit low fan tip speeds for fuel burned, DM , and noise. For example, Pratt 6 best fan performance while maintaining proper core Whitney (and the aircraft manufacturers who as- boost pressure at a high efficiency. The booster sisted them) estimated SFC advantages of 3-112 to also offers a reduction in foreign object damage 4 percent, fuel burned (block fuel) advantages of to the core by allowing such objects to be centrl- 2 to 4 percent, and DOC reductions of 112 to 2 per- tuged into the bypa3s stream. The high-pressure cent over a separate-flow exhaust. Noise advan- compressor is an extremely advanced machine incor- tages over a 3/4-length duct configuration ranged porating high efficiency, low aspect ratio (long from 0.4 to 1.1 EPNdB. Moreover, the mixer was chord) blades to minimize number of blades and to considered a mechanically simple, high reliability provide ruggedness for reduced performance deterio- system of low development risk.

ration with time (both factors in maintenance cost).

Active clearance control is used for the last five 'rhe geared engine versus direct-drive engine stages, while the inlet guide vanes and first four evaluation was not as conclusive, particularly for vane rows are variable. The basic design of the fuel burned and DOC. Fuel burned for geared en- compressor was based on the NASA Advanced Multi- gines was sensitive to gearbox efficiency and Stage Axial Flow Core Compressor Program.

weight, while DOC was sensitive to initial cost, maintenance cost (e.g., gear replacement frequency), The combustor is a double-annular, low emis- and fuel burned. For a range of reasonable esti- sion design derived from the NASA Experimental mates for these values, a wide-spread variation In Clean Combustor Program. This design concept pro- hurl burned and DOC was achieved, particularly vides the staged burning necessary to meet emis-

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slona requirements, but In a short compact design. critical transients occur, while permitting tighter The high- pressure turbine is a two-stage, cooled, clearances during cruise - hence increased etfi- high rlticirncy design Incorporating ceramic tip ciency. Another contributing Item to reduction of n h rxud n and active clearance control. Itlrectlon- m„intenancr costs and weight is the large reduction ally solidified Rvne 150 material is planned for In number of airfoils, primarily in the hot sretlon the airfoils, along with improved cooling trcltnol- for Pratt 6 Whitney and In the compression system ogy. The low-pressure t,obinr is a live-stage un- of the General Electric design, as comparrd to the cooled design. Improvements a wore projected as reference engines. This occurs because of the use result of improved concentricity. sealing, and of low- aspect- rat to boading as well as a reduction roundness control (v.g., an unsplit impingement in nuintirr of stages.

cooled case is used). The mixer consist" of 24 Acoustic reduction feeturea of tho u two engine chutra contoureJ for effective, low-loam mixing des:gna are also similar. A large chord-spacing of the hot, high velocity core gas with the low- is used between the fan rotor and outlet guide vrlocity fan stream.

vanes to miulmize tan noise. Ilia- mixer Is expected The Pratt 6 Whitney conf i guration is Illus- to reduce jet noise considerably. Low-pressure trated in figure 12, along with associated key com- turbine noise is reduced by •election of numbers of ponent technologies. Ilse tan is a sinxle-stage, blade”. Extensive nacelle treatment is utilized In shroudless design with hollow-titanium blades the tan inlet and along the fan duct walls.

laving an aspect ratio of 2.8. A tour-stage, 1.77 The conceptual eng ate designs offer the poten- pressure ratio low-pressure compressor supercharges L tial for axcreding the SVC and rXX: goals establish- the core. It uses hupercritical. :anted airfoils project. Predicted benefits ad by NASA for the to minlmleu losses and provide high surge- n4,rgin.

are summarized in figure 11. These values reflect the high-pressure comprrn or im a high inlet cor- the projections of both engine manufacturers as rected tip speed design with low aspect ratio well as the aircratt manufacturerh. As cast be (1.7:1 average) blades and variable stators in the avert, the goals are exceeded in all cases. Other first four stages. The .otor tips extend into goals for performance deterioration, emissions, grooves (trenches) in the abradabl y rub ► trips for noise, and growth capab:lity were also exceeded, reduced losses. A modulated, ach y .• clearance con- hence providing margin for an advanced technology trol system is used on the last seven stages.

program such as the F. project.

Multiple circular arc airfoils are timed for the supersonic and transonic front stages, while super- These engine definition studies established critical airfoils are used for the rear stager. the beat-.- design parameters around which the cur- rent component development and integration program The combustor is m low emtsmlons vorbix was planned. Schedules for the current activity (staged vertex burning and mixing) design Liming two are shown in tlgure 14 for both contractors, show- axial stages. It in derived from the NASA Expert- ing the major project elements. A continuing de- mental Clean Combustor Program. Iltr high-pressure mign and anslysim effort will be conducted to sup- turbine is a singie-stage design with mingle crys- port the component, core, and integrated cure/low tal alloy blades permitting high metal temperatures, spool efforts and to use data from those efforts hence minimizing compressor bleed cooling air.

for refinements of the previous engine definition Nigh efficiencies are expected, with the design in- studies.

corporating large annulus area, low loading coeffi- clients, high rotor spaed, high rim speed, contoured The component technology and development Ac- endwalls, preswlrled coolant flow injection, hot/ tivity will be conducted on all components of tic cold modulated active clearance control, and ceram- engine (excluding the composite nacelle which lA ic outer air seals coupled with abrasive blade not a part of the experimental effort of the E tips. The low-pressure turbine has four uncoulyd project). When sutticLentl y developed, the high stages said is counterrotating relative to the high- pressure components will be assembled and teased to pressure turbine to reduce camber of the first- evaluate component Interactions and core perfor- stage airfoils and Improve performance. It also mance. Upon satisfactory core demonstration, the lass active clearance control. To reduce weight, low-spool components (fan, low-presmure turbine, the rear stages will be fabricated from titanium and mixer) will be assembled with the cure and a aluminide. The mixer consists of a 12-lobe scal- metal boilerplate nacelle. Ibis integrated package loped configuration. A flight mixer would be made will then be tested to evaluate uninstalled per- in one piece through superplactic forming and dif- formance, interaction, and mechanical systems fusion bonding of titanium.

(e.g., active clearance control) operating charac- teristics.

Both engine msnitacturers oeid particular at- tention in their o.e.lgns to minimizing performance Advanced Turboprops deterioration and maintenance coots. Both engine configurations texture is short, stuff. straddle the third ACF.E propulsion effort is the Ad- mounted core with easily accessible bearing com- vanced Turboprop project. This project has the ob- partments. Roth used five main bearings and two jective of providing technology readiness for ef- bearing r.)mpartmentm. Special attention ham beet.

ficient, economic, ^nd acceptable operation of given to structural load carrying to minimize turboprop-powered commercial transports at cruise Sine bending forces encountered furing flight.

aprro:s up to Mach 0.8 and at altitudes above 9144 m Structurally integrated composite tan ducts, core (10 000 ft). This technolog y would also apply to cowls, and fan frames are used to stiffen the en- cargo aircraft, short-haul operation, and to new pine cases and reduce inner caming distortions.

military aircraft requiring long-range and long- Nacelle '.oad-mharing is augmented by extensive use endurance subsonic capability. The goal is to of active clearance controls on the compressor, achieve at least a IS percent fuel savings relative high-pressure turbine, and low-pressure turbine.

to a turbofan engine with an equivalent level of This permits clearances to be opened up at oper- core technology. This goal, o1 course, must be ating conditions where maximum flight loads and achieved with a cabin environment which is accept-

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able (i.e., as c.Mfortable and quiet as today's attenuation concepts along with Identification of Irt-powered commercial transports). the impact of propeller nolae characteristics un fuselage design. Efforts in installation asrody- !reviously, In the 1950s, turboprop-powrrrd nomic n will establish the , effect and extent of aircraft were in r.mmrrclal service at speeds of propeller/nacrllr/wing interactions and will Iden- Mach O.b to 0.65 and at attitudes about lb():, in tity improvements available through nacellr/wing (25 000 ft). lfiese were replaced by jot-powered t n tloring. Finall , me,b anical component goals y aircraft which otfervJ higher speed, above-the- are to establish conceptual designs for turboprop wrather cruise, better passenger comtort, and sim- engines with improved gearboxes and pitch change pler maintenance. In an era of inexpensive fuel, and to identify potential Improvements va-olranirtns, efficiency was not a critical factor and was offset relating to the reliability anti maintenance rusts.

by the higher productivity of the let@. Now, how- Some results and status of the arras are described ever, the application of several advancrd technol- as follows.

ogies (e.g.. advanced aerodynamic capabilities and understanding, improved n trnrcturst concepts per- Propeller/Nocrlle• mitting thin, high-speed, swept-tip blade labrics- tioni etc.) permits the turboprop propulsion system The propeller and Its naco.to tnuxt be designed to once again he considered. An example of this to achieve high efficiency at :ruler spends up to evolution in turboprops, in this case a scale model Mach 0.8 and 9144 to (10 000 It) sltitude. The pro- mounted In the Lewis Research Center 8- by b-toot peller bladi,, must be very thin and will require wind tunnel, is shown in figure 15.

swept leading rdges in order to minimize compressl- A number of aircraft and propulsion system billty losses. The spinner and nacelle will re- studies have indicated the potential of this con- quire shopping to minimize choking and compressi- (8-19) R, • cept. sults from three of the earlier bility loores, especially near the blade roots.

studies are shown in Itgure • s lb slid l7. Boeing At this tine, four propeller models have been and Lockheed examined 1985 tecltttology level turho- tested (designated by the model number n SR-1, SR- shatt engines versus equivalent technology level 1M, SR-1, and SR-1). rhese models were all 62.21 turbofan engines (i.e., JTIOD level of technology).

cm (14.5 in.) diameter ..ltd were designed by Ilamll- The Boeing aircraft design wax based on 197b tech- ton Standard unde contract to Lewis Research Cen- nology levels, while Lockheed used 1985 technology ter. Plantorm and significant design character- levels (i.r., supercritical airfoil, active con- istics are shown in figur 18. The model• all lied trols, etc.). Douglas used the DC9-10 as a basis eight blades and were designed to operate at Mach of comparison and compared both current technology 0.8, a t1p speed of 244 m /arc (800 ft/r :), and a level turboahatt engines (TSFC-0.b5) end 1985 tech- disk power loading of i01 kW/m (17.5 slip/f[ j.

nology level engines (TSFC-0.51) to the current Tip sweep was varied, however, for values of 00 DC9-10 configuration using low-bypass-ratio JTBD (SR-2), 10" (SR-1, SR-IM), and 45 0 (SR-)) as shown turbofan engines. As can be seen, a wide spread in figure 19. SR-2 was basically a baseline de- in furl a wings and t1OC was achieved, reflecting sign against which the effects of seep were to be various assumptions (r.g., propeller ellictency, e • va l uate a . SR-1 and SR-IM differed primarily ',r fuselage concepts and weight for noise attenuation, the blade twist and camber distribution from hub to aircraft configurations, design stage lengths, tip. SR-1 was modified into SR-1M when results of maintenance costs, etc.) of the three different ap- initial wind tunnel testing showed radial loading proaches. In all cameo, however, there is a very dlttered from design distribution. The changes significant improvement for the turboprop-powered were designed to increase loading in the ootboad aircraft as compared to the turbofan-powered air- region of the blade. SR-) was the first model to craft. This is especially true at the shorter be designed with acoustic consideration (fig. 15).

stage lengths and is one reston why ad inced tur- Because of this and other relinements in the blade boprops look particularly attractive for the short- design procedures (taking advantage of previous slid medium-range flight markets currently being testing on SR-1, -IM, slid -2), the design effi- served by the DC-9, B-717, and B-727 aircraft.

ciency of SR-1 was higher and the estimated cruise These studies identified tour major arras as near-field noise level was lower than for the other being important for l,w fuel consumption, low op- deaIgns. Two types of spinners were also designed ."

,rating cost, and passenger acceptance. These and tested - one was conical slid the other was area \t, fit areas - prop,^Iier/nacelle, cabin environment, in- hub region ruled to lower flow velocities stallation aerodynamics, and mechanical components where choking could be a problem.

are all being addressed in Phase I of the Advanced Initial testing of SR-1 and SR-2 was conducted Turboprop project. This phase is an enabling tech- by Hamilton Standard (undri NASA contract) in a nology effort, directed at evaluation of concepto, wind tunnel at United Technologies Research Center.

development of theory, and acquiring supporting (20.21) These tests gave the first experimental data for the four key technical areas. Lewis Re- confirmation of the expected pr..pulsive efficiency search Center manages this effort with support of gains for advanced turboprops. A comparison to Ames (Installation aerodynamics and aircraft 19',0-era turboprops (r.g., Lockheed Flectrm) and to studies), Dryden (flight testing), and Langley high-bypass-ratio turbofans is shown in figure 10.

(cabin environment).

Subsequently, all models have been tooted in In the propeller/nacelle area, the goals are the Lewis Research Center N- by b-foot wind tunnel.

to establish aerodynamic and acoustic design meth- Test date are shown In figure 1l for a range of odologies for high-speed propellers (and associated Mach numbers. SR-1 is seen to have the brat per- nacelle and engine inlet) and to select a viable formance above Mach 0.75. Also, preliminary re- baseline propeller design (including fabrication sults indicate the predicted reduction in noise technique) for future phases in which effects of wan achieved. Further, the area-ruled spinner per- scaling will be evaluated. For the cabin environ- formed better than the conical spinner. (Note ment area, the goals are to identify merits and that retwisting of SR-1 to SR-1M did not affect tradeotf characteristics of vari wrs fuselage noise •..e.w -...-, .« .- . =. +eWWWWstl +famw -M EN aesl...4EWM00.0"We 4teAA W

- T i

i

the perfotmance at the design Mach number as pre- models on a IetStar aircraft (fig. 22). The models woxuld be mounted obovr the fuselage, which would be illcted.) other tests, not shown, varied tip speed and cower loading trom destgn conditions. ltlli- Instrumented with microphones, This approach toes ciencir n above 80 percent were achieved with the been taken because of the uncertainty of high-speed lower power loadings (but In actual operation, this wind-tunnel acoustic data with respect to both would give a larger pt'opelier diameter which dust level and directionality. Also, such uncertainty he considered In the aircraft opt lmleatien). is extremely difficult to quantity without compar- ison to flight data.

other propeller model@ are currently in the program to investigate effects of designing for For fuse:age attenuation, three different fuselage structural concepts have been suggested to different tip speed, loading, and nuriber of blades, along with advanced airfoils. Results to date, date. A conventional fuselage in believed to at- tenuate nulbr as si own In figure 21. llie least at- however, Iriwn an efficiency std ndpoint, are con sid- tenuation occurs in -.he frequency ran K - of several @red promising. The previously mentioned studies assunw-d is value of 80 percent for propeller etfl- hundred hertz. Cntoru.anstely, the blade passing clency. improvements continue to be made in pro- frequencies of many propeller designs fall in this peller ae rrofvnamlc design methodology based on test range. The three concepts to resolve this problem results and analyrir, South improvements are ax- are: (1) Structural tuning and damping, which .,I pected to result l.` achieving or bettering the seems to apply at the blade passing frequencies current propeller designs, (1) Increasing tu*elaKe value of 80 percent efficiency ai. design loading stiffness, which is more eftective at lower fre- and Mach number. Results, as they are obtained, will also continue to be factored into aircraft quenclea as cou l d be achieved by lower propeller Lip speed• (sr-, of course, lower tip speed* are studies to provide guidance as to the optimum de- also an effective w v to reduce propeller generated blgn 'onditlons.

noise); and (J) using a dixible-limp-wall approach In addition to the propeller effort directed to h ydering t,aonant frequencies while increasing at efficiency, work is also planned to evaluate damping. This letter concept to more effective propeller fabrication and aer- •tasticity. The with higher blade sassing trequencies as could be basib approach to construction of the thin, highly- achieved with increased number of blades. Current swept blades is to use modifications of the metal plane are to analyze these concepts and run model n par-composite shell approach as cossser •.tally de- or panel tests for scrcen[ng their effectiveness veloped by Hamilton Standard. Fabrication samples in providing maximum noise attenuation with mini- and seroelastic models will ebtablish the tesst- mum weight penalty.

b111ty of using this or other method&.

Installation Aerodynamics cabin Environment The initial aircraft studies identified the ro be competitive with turbofan aircraft, Integration of the turboprop propulsion system with cabin environment during cruise for n n advanced the airframe as one of the areas of high uncer- turboprop aircraft should be equivalent in noise tainty, ,,articularLy because of tl • e possible large and vibration. The ^.rise perceived by the passen- interaction between the slipstream and wing. These ger lnsi the cabin is a strong function nu: only r 'e interactions could be particularly revere for a of the .. , fee generated by the propellers but also supercritical wing. The section of the wing in the of the noise attenuated by the fuselage. Since slipstream can operate into drag-rise, ettectively the propeller tips may be slightly supersonic at reducing the installed performance of the propel- the Mach 0.8 cruise condition, the resulting near- ler. In addition, the propeller will be subject field noise level is expected to be quite high.

to a nonuniform flow field created by the airframe, Thus, it is likely that additional airtram weight

ij

thus potentially reducing its performance. Con- (over a turbofan-powered aircraft) will he required versely, there is a possibility for swirl recovery, to achieve the required attenuation. The quiet thus increasing the performance of the installed cabin environment is thus achieved at the expense propulsion evstem.

of fuel economy.

ro reduce the uncertainties associated with Currently, there are four approaches to this the installation of these advanced turboprop pro- prob l em (i) Design propeller tip speed can be pulsion System, a combined experimental and analyt- reduced to lower the noise generated by the pro- ical research program hab been initiated by Ames peller. (2) Fuselage design and can acoustic treat- Research Center. Both a slipstream simulator model ment can he Improved over conventional techniques and a powered semiSpan model will be tested. To to increase noise attenuation. (l) The propeller date, only preliminary results from tests of the and fuselage design can be Integrated to the selec- slipstream simulator in the Ames 14-foot wind- tion of propeller blade passing frequency and fuse- tunnel are available (fig. 24). These results do lage acoustic modes. (4) Finally, the engine loca- Show that the drag penalties associated with the tion on the aircraft can be optimized; for example, interaction of a turboprop slipstream and a super- mounting the engines farther outboard on the wing, critical wing are not excessive, and that the po- or on the sit end of the fuselage becind the pas- tential does exist to recover some of the propeller senger cabin, would result in less cabin noise.

swirl losses with the wing. lfie reason for the All four approaches, which affect propeller effL- h o apparent anomaly at a swirl In not known, but it clency, diameter, and weight, will require exten- will be investlk.sted tutther with the powered semi- sive aircraft optimization& and tradeoff studies.

span model tests.

i First, however, near-field noise data on propellers, as influenced by design parameters, is required.

Mechanical Co m jonent n To obtain high quality acoustic data with The fourth area to be addressed in the Ad- i respect to noise level, spectral content, and di- rectionality, NASA is planning to conduct flight vanced Turboprop project involves evaluation of the teats of the 62.11 cm (24.5 in.) diameter propeller reliability maintenance costs of the advanced pr.

a

b -vistalk ^ e JuctvJ, so previously described. Future phases, to yeller anu gearbox, along with conorptual screening e- valuate and Jrstgns for advanced gearboxes, pitch change fully establish technology readiness, will mechanisms, slid rnglne drive systtmus, re date, a scale• effects relative to propeller generated studv of turboprop reliability and maintenance noise, , fuselage nolss attenuation concapts, proprl- costs has been cosnpleted by Detroit Utesel Allison ler flutter, and propeller fabrication. Flight (DDA) under contract to Lewis Research Centvr.(22) testing will be required to achieve- viable data ill rhv objectives were to determine actual maintenance these areas and to evaluate system interactions In this way, :oats of past turboprop systems and then project under flight operational conditions.

the potential at the advanced turboprop system rel- such costs for new turboprop systems in the 1985- 1990 time period. H antlltoit Standard assisted in ativr to fuel savings and cabin environment can be the evaluation of the pr , ',,Vlier data. The aircraft established for cosmnercial acceptance.

Involved were the Locl, 'aved 1.I88 Electra, Convair Concluding Remarks CV580, and LockhvvJ 1382 Hercules. Theme were all powered by Lite DDA 501-DIl tutboshaft engine and Potential ben.-tits of the thre• r WILL propul- either the DDA b0b p^opeller or the HS '+4HbU pro- sion retorts for coslrmerciol air tr , .nopotto art, peller. Data was obtained Fran airline records, outside repair facilities, CAR form 41, and the DDA shown in figure 28. In EC1, as much as S percent fuel savings said 1 percent DOC reduction ran be reliability and maintenance department records.

very ap- realized by the early 1480,, thus bring Figure 25 shows the results of this study, as ai e near-trn needs of the airlines.

pllrable to th cost of con.pared to the fully burdened maint •-nonce F hent, lits represent a major reduction in luel the H-73i aircraft.

Lite JT80 turbofan that powers savings slid Ik1C and could bo realized In the late lit this comparison, the actual turboprop malnte- 1480s In new engines or In dt• tivative engines by nnace cost of $42.10 per flight hoxur in CY 1416 the middle 1980s. Advanced turboprop benefits dollars was scaled to $51.18 to reflect the scaling might be achieved by the late 1980s or early 1940, of the turboprop to d thrust capability equal to and represent the largest potential of any ACES the JT811 turbotan at Mach 0.8 and 10 670 m (35 000 project. lnderd, the advanced turboprop provides that the bulk of the ft) altitude. It can be ov e n an almost unmatched technological opportunity, maintenance costs reflect the older technology core possibly leading to a step gain in subsonic air- of tier l)DA501-D1) engin e . although there is still TO realize such gain, however, craft etficienrv.

a subetan t al difference between the propeller/ will require d major change in propulsion systems gearbox and tan/thrust reverser. For future engine from those in current use. For this reason, ad- systems, it can be assumed that the maintenance othe r vanced turboprop concepts may first spprar to cost of the core will be no greater for a turt • o- types of sircrsfi^.

prop titan for a turbotan if the same level of tech- prrhrnt an In aoitmary, these three projecth r.

nology is used. I'hus, it turboprop maintenance aggressive and focused .approach to developing fuel costs are .o be comparable to thome of a turbotan Further, their efficient propulsion tvchno o lugV.

engine, the propeller/gearbox maintenance costs impact on future aircraft propulsion systetns is must be reduced to the level of the tan/thrust believed to be large and of major consequence.

reverser.

Various cost drivers and design features of Rrleren,es Lite 501-D11/54H60 system were examined to deter- mine where maintenance cost savings could be ex- 1. J. F. l+ugan, D. P. Bencze, slid L. J. Williams, pected. Then, unburdened costs for that svatem "Advanced Turboprop Technology Development."

were projected to an a.lvancrd design of 1990, as- AIM Paper 77-1223, Aug. 1477.

suming that various design leatures were incor- 2. "The Next Commercial Jet Transport: The Need, porated (tig. ?b).

Economics, Technology, and Financing," Paper Elimination of scheduled removals accounted presented at the Air Trans port at ton Research for 0-percent of the cost saving. Modularity in International Forum, San Francisco, Mav 4, design contributed another large fraction. For 19/1.

the gearbox, other items included provision for 3. "Alreralt Furl Conservation Technology - Task more modern design tcatlres such as longer life Force Report," NASA-Office of Aeronautics and bearings, removing engine accessories from the Space Technology, Washington, D.C., Sept. 10, gearbox and mounting them on the- core as is the 1475.

case for a turbotan, and using a single shaft drive for aircraft accessories. With all these features, 4. "Fuel Cost and Consumption," Civil Aeronautics the unburdened maintenance costs were projected to hoard, Washington, D.C., Dec. 1977.

be $0.73, dhout a six to one reduction.

"Airline Industry Economic Report," Civil Aero- 5.

Values of this order were usrd it the advanced nautics Board, Washington, D.C. Vol. X-4, turboprop aircraft studies previously described.

Feb. 24, 1478.

Since such costs could be higher in acru:al prac- b. D. E. g ray, et al., "Energy Efficient Engine tice, the affect on DOC of doubling the maintenance Preliminary Design and Integration Studies - costs wiliav ^ tuatrd using data from two of the Final Report," NASA CR-135396, (to be publish- studies.(( )) As shown in tlgure 2b, the effect I-20628).

ed, NASA Contract NAS Is small.

i^ 7. R. P. Johnston, et al., "Energy Efficient En- Future Effort gine Preliminary Design and Integration Studies - Final Report," (to be published, Currently, NASA is to Phase I of n multi- NASP. Contract NAS3-20627).

phased Advanced Turboprop program, Phase I is an S. R. E. Nettzel, R. Hirschkron, and R. 11.

enabling technology phase that to estimated to re- Johnston, "Study of Trbotan Engines Designed quire aLout 3 years to accomplish. Fffort in all four of the major technical areas is being con- for Low Energy Consumption," (R7hAEG432,

r a General Liretric Co., NASA Contract NAS1- 19;01.) NASA CR-111051, 1976.

v. K E. Neltswl. R. Hirschkrnat, and R. F.

to ntaton. "Study of Unconventional Aircraft Enlltnes Designed for Iwws E-iergy Consumption."

(R76ALG597. General Electric Co.. NASA Con- tract WAS I- 19519.) NASA CR-1151{6, 1476, 10. D. E. Clay, "Study of I'urbotan M.ugines hreignt."

for tow Energy Conaumpttim." (PWA-1i111, Pratt 6 Whitney Aircraft, NASA t'tnttract NA.Sf-19112.)

NASA CK-115002, 19743.

11. D. C Gray, "Study of Unconventional Aircraft Engines Designed for l.w Energy Consumption," (11WA-14 W, Pratt t+ Whitnev Aircraft, NASA Contract NAS1-194435.) NASA C111-115065. 147b.

12. R. I.. Foam, and J. P. Hopkins, "Fuel C.ntmeiva- tion Potential for the l'me of "urboprop 1'.w+r- planes," SAE Paper 760511, May 1976.

11. J. P. Hopkins and H. E. Wharton, "Study of the Coat'Henettt Tradeoffs tar Reducing the Ener- gy Consumption of the Cwmw • rcial Air 1'rans- portation System," (1-R-27769-1, lwickhrrd- Calitornia Co., NASA Contract NAS2.11612.)

NASA CR-117917, 101b.

C t J. P. Hopkins, "Study of Lite Cost'& netlt 14.

i Tradeoffs for Reducing the Energy Coin- mption of the Ctionrecial Air Transportation System," (LR-27769-2, lockhred-Calltornts Co.; NASA Contract NA.92-8612,) NASA CR-117926, 1976.

15. J. Stern, "Aircraft Proptulsion - A Ke y to Furl Conservation: An Aircratt Manufacturer's View," SAE Paper 760S18, May 147b.

16, E. F. Kr+..w, "Cost/8rnrflt Ttadrolle 1 "I Kr- ducing Lite Energy Consumption of Commercial Air Transportation System. Vol. I: technical Analysis," (Mix'-J%i40-Vu1.-1, D.xiglas Aircraft Co., Inc., NASA Contract NA.S.-8618.1 NASA 1916.

CR- l 1. 42 1 .

17. .1. C. Vanahkoude, "Coat1heuetit Tradeotts for Reducing the Fnergy Consumption of Comurcial Air Transportation System. Vol. II: Market and Economic Analyses," (MIX'-J7340-Vol. -2.

Douglas Aircratt Co., Inc., NASA Contract NA52-8618.) NASA CR-137924, 19743.

111. "Energy Consumption iliaractertatic n of Trans- ports Using the Prop-Fan C4ncrpt: Stmmvrv," (Db-15780, Hoeing Commercial Airplane Co., NASA Contract NAS2-9104.) NASA t'R-1379is.

V

197b.

19. "Energy Conntmption Characteristics of Trans- ports Using Lite Prop-Fan Concept: Final Report," (Oh-71780, Hortng C..mmrrcial Air- plane Co.; NASA Contract NA.S2-9104.) NASA CR-137937, 1976.

20. C. Rolirbach, "A Report on the Aerody+, amic Dr- sign and Wind Tunnel Test of a Prop-Fan Model," AIAA Paper 76 -bb7, July 197b.

21, D. C. Mikkelson. K. J. Klmha, G. A. Mitchell.

Hikets, "Design and Performance of and J. E.

Fnergy Efficient Pro pellers for Mach 0.8 Cruise," SAE Paper No. 7704111, Mar. 1977.

22. P. C. Stolp, and J. Hium• "Advanced Turboprop Propulst.n Sys!.». Reliability and Maintenaner Cost," SAE' Paper-771000, Nov. 1977.

-b r

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FUEL & OIL F CREW © MAIM.

UEPR. & OTHER I INTER"o'-TIONAL TRUNKS UOh1ESTIC TRUNKS B727 200 DOC FRACTIONS 1974 1975 1976 1417 YEAR ,Iure 1. - U. S. airline jet fuel price. Monthly average.

t terM cm %^ myl i wwmT III r I^1 f

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MATT & *"IIWV rTM figure ?. - En gines under investi gation In fnginr Component Improvement profert, iS c'1uF

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ENGINE IMPACT /OPERATIONAL ASSUMPTIONS: • PERFOR MANCE (THRUST. SFCI / MISSION PROFILES, ROUTE • WEIGHT / STRUCTURES, FLEET A10DELS, • PRICE / USAGE RATES • MAINTENANCECOST • OTHER (NOISE, ETC.

i ECONOMIC ASSUMPTIONS.

/ USEf UL ENGINE L R. MARKET PROJECTIONS, DEPRECIATION, IMPACT "IRCRAIT TAXES, FUEL PRICE, AIRI INE 1 ^ ?ERFORh1ANCE (PAYLOAD, , HURDLE RAZES BLOCK FUEL. ETC. ► • (:UAIULAT IVE FUEL •PRICE • NIA INTENANCE COST SELECTION • OTHER (NOISE, OPERATING r • FUEL SAVINGS tBLOCK EMPTY MIGHT, ETC. ) FUEL, CUMULATIVEI f • ECONOMIC BENEFITS • AIRLINE ACCEPTABILITY ECONOMIC IMPACT • PRODUCTION POTENTIAL • RETROFIT POTENTIAL • DIRECT OPERATING COST (LwC ► • RETURN ON INVESTMENT (R011 • DEVELOPMENT RISK I • AIRLINE PAYBACK PERIOD • NASA COST Figure 3. - Concept evaluation procedure for performance Improvement engine component improvement project.

r ^ TAT

' ' 1 ' 1

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t CUMULATIVE FUEL SAVED SF( REDUCTION THROUGH 2005 - x 04CEPT ENGINE ; CRUISf ;06J1TER,J__0 A C1L IRENCHED HPC BLADE TIP JTBD 0.9 2229 509 REVISED HPT OUTER AIR SE41 JT8D 0.5 341 90 HPI ROOT DISCHARbL BLADE JT8D 0.9 9NO 159 DL-9 NACELLE DRAG REDUCTION JT81) 3.5 322 85 3.8 ASPECT RATIO FAN JT9D 1.3 1725 720 TRENCHED HPC BLADE TIP J79D 0.3 1865 433 HPT ACTIVE CLEARANCE CONTROL JT9D 0.9 1171 468 HPT VANE THERMAL BARRIER COALING JT9D 0.2 530 259 HPT CERAMIC OUTER AIR SEAL JT9D 0.3 1953 IMPROVED EAN CF6 1.7 3997 1056 NEW FRONI IMIUAT CF6 0.3 800 211 HPI AERODYNAMICS CF6 1.3.1.6 1110 296 HPT ROUNDNESS/CLEARANCE CF6 0.4-0.8 1506 39b HPT ACTIVE CLEARANCE C04TROL CF6 0.6 916 141 LPT ACTIVE CLEARANCE CONTROL CF6 0.3 348 SHORT CORE EXHAUST CF6 1.0-3.0 1730 457 DC-- "TDUCID ENGINE BLEEn CF6 0,1 3029 ROO

FlgorP 4 Summar y d results from evaluation d performanre improvement cnni epts. Enyine

Component Improvement project.

i 1.

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I t i AV RIPAIRID INGINI TREND RICOVI RY DIII TO f fRCf NTAGl RI PAIR f NGINI INCREnSt_ IN Sri CIFIC Full r CONSIIMP HON j S14OR I TI RM I ON TTRM DF RRIORA 110N DI T1RIORATION^ 1I11f — ^ i I " IARIY FlIII Ol'i4ATION RU 1 M I I RATION L— r VII l D Cill CKOII I ! I iqure 5. SFC performance tMotvrioration trends.

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Figure 7. NASTRAN predictions compared to engine data

for short-term deterioration.

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(150 FLIGHTS) ^^ TESTING (150 -' FLIGHTS) FRONT VIEW Figure F. - Fan rub patterns. Analytical versus experi- mental correlation.

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1981 1 I C Y1 1977 1 1978 1 1979 1 1980 1 PERFORMANCE •IMPROVEMENT •F LAS IBILITY ANALYSIS *GROUND & FLIGHT TEST ENGINE DIAGNOSTICS • HISTORICAL DATA I •IN-SERVICE DATA *SHORT-TERM DETERIORATION •LONG-TERM DETER IORATION *COMPONENT SENSITIVITY •DATA ANALYSIS & MODELING — -- G. I- Q P & WA Figure 9. Engine component improvement project schedule.

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t^ PRATT L WHITNEY GENERAL ELECTRIC IT91)4A ILI, EEE CF6-50C :)1RECT FAN DRIVE DIRECT DIRECT DIRECT SEPARATE EXHAUST CONFIGWATION MIXED MIXED SHARATF BYPASS RATIO 511 6.55 7.0 4.3 FAN PRESSURE RATIO 158 1.14 1.61 1.72 COMPRLSSOR PRESSURE 10 14 22.2 12.9 RATIO OVLRAL1 PRESSURE RATIO 25.4 38.6 36 32 TURQINf TEMPERATURL

MAXIM("' CRUISE ( 0 0 1088 1204 1182 1138

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HOT-DAY TAKEOFF ( 00 1252 1343 1338 1316 " (OF) 2285 2450 2440 2400 SLS THRUST (Lf1S) 44,265• 39,250 36,500 39,5800 (KN) 197• 174 162 116• 'SCALED VERSIONS OF REFERFN(f fNGINFS

Figure 10. • Cycles selected for energy efficient engines (maximum cruise

conditions).

ACTIVE CLEARANCE CONTROL 'THIN, ACOUSTIC NACELLE

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I y,,.+ ,I. ^s r EXHAUST .bt- ^,md -- -- MIXER ' i SINGLE-STAGE ' `CO-ROTATING ^TEN-STAGE ; SPEED FAN FIVE-STAGE HIGH-PRESSURE LOW-PRESSURE i COMPRESSOR TURBINE I I 1 4-STAGE ' DOUBLE ANNULAR ! ` HIGH EFFICIENCY ISLAND WiO-STAGE BOOSTER S COMBUSTOR HIGH-PRESSURE TURBINE Figure 11. - General Electric's energy efficient engine configuration.

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ACOUSTIC LOAD-SHARING'I Y •.

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TEN-STAGE COMPRESSOR J 1HANSONIC • HIGH PRESSURE SINGLE-STAGE COh1PR_SSOR HIGH PRESSURE TURBINE Figure 12. - Pratt & Whitney's energy efficient engine configuration.

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0 4 2 6 8 10 12 14 16 18 20 .I IMPROVEMENT OVER CURRENT ENGINES, percent reduction i Figure 13. - Potential benefits of energy efficient engines.

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,y t, ENERGY EFFICIENT ENGINE PROJECT SUMMARY SCHEDULE 1978 1979 1980 1981 1982 1983 CY DESIGN AND ANAEYSIS E 1 COMPONENT TECHNOLOGY AND DEVEL- OPMENT , TEST l TEST 2 CORE TEST 1 TES T 2 TEST INTEGRATED COR111 m SPOOL IESI © PRATT & WHITNEY =GENERAL ELECTRIC figure 14. - Summary schedule for energy efficient engine project.

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Alain ..i ilqure 15. - Hi g h-+prod propeller modal mounted in I owls RP%eaf(h Center B- by 6-foot wind tunnel, ^)R1ci^^AL^,Pl',YI OF

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5BOEING AFT-h1OUNTED _RESPECTIVE TURBO- PROP-FAN FAN (REFERENCE) ' 1 1 0 500 1000 1500 2000 n. mi.

L 1 i 1 ___L_ _. 1 _._._. L _ 0 500 1000 1500 2000 2500 3000 3500 km ► STAGE LENGTH iSTlll AIR Figure 16. Advanced turboprop iprop-fan ► aircraft fuel savings.

a V r ,'f It STAGE tF DOUG EA S LENGTH, (i DC 9-30 km n. mi.

PROP- FAN 1(10 (1 1:+57 TSFC • 0.65 ••^ .

10 r 537 290 X10 r` 475 LOCKHEED 1500 277A =^ PROP-FAN .

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.t 30 40 50 60 0 20 FUEL PRICE, c gallon (1973 CURRENCY) Fiqure 17. - Advanced turboprop (prop fans aircraft operating cost i savings.

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SR-2 SR-1, IM SR-3 TIP SPEED, 24418001 244 18001 244 18001 misec (ft sect I POWER LOADING, PID 2, 301 137.51 301 (31.5) 301 137.51 MW (shp,ft21 NO. Of BLADES 8 8 8 TIP SWEEP 0 30 45 ANGLE, deq a DESIGN EFF., % 77 79 81 } DESIGN NOISE 143 137 LEVEL, dB I iqure 18. - Design characteristics and planform of high-speed propeller models.

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figure 19. - High-speed propeller models.

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60- Z1'^^1Z1Ztr a W N HIGH BYPASS TURBOFAN .5 .6 .7 .R .9 CRUISE MACH NUMBER PROJECTION BASED ON 1976 MODEL WIND TUNNEL TESTS.

Figure 20.

- Propulsive efficiency.

LEWIS 8- BY 6-foot WIND TUNNEL I .. 3. 06, C 1.7 P 82 — i 80 Z— ` i l eR F A { MODEL SWEEP SPINNER o t10 AREA RUIEh O SR-2 I ce SR-1 300 CONIC O A ^ 74 SR 1M 300 CONIC A SR-1N1 300 AREA RULED SR-3 450 ARIA RULED O i

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k r- INC,'EASED STIFFNESS TUNED STRUCTURE DOUBLE LIMP WALL ti m I d / i CONVENTIONAL FUSELAGE FREQUFN P "', Hz Figure 23. - Fuselage noise attenuate^n.

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SLIPSTREAM SIMULATOR U elf Q EJECTOR z DRIVEN NACELLE—' = U -1Ol^ 0 3 6 9 DESIGN SWIRL ANGLE, deg Figure 24. - Slipstream simulator results.

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t $53. 18 ;. M60 PROP 4. 12 (;1 A R H 0 X 02'1 1.53 -, $30.47 1 AN 1.83 THRUST ',01 -D13 14VERSER 45.24 INGINf & INSTALLATION 1TKD COW & 27. 11 INS IAl LA TION SCALED TURBOFAN TURBOPROP IB-737)

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1 iyure 25. - Maintenance cost comparison for 1960-era turboprop versus turbofan, fully burdened in 1976 dollars per flitlht hotir.

I ^ ^ $4.58 IMPROVED FAULT ISOLATION & DIAGNOSTICS PROP AVOID SCHEDULED RE410VALS $2.26 SIMPLER, MODULAR DESIGN MORE RELIABLE HEATERS I AVOID SCHEDULED REMOVALS IMPROVED DESIGN FOR LIFE & RELIABILITY USE LONGER LIFE BEARINGS GEARBOX REMOVE ENGINE ACCESSORIES & DRIVE $2.32 RFMOVE AIRCRAFT ACCESSORIES & SIMPLIFY DRIVE MODULAR DESIGN SCALED $0.73 1960-ERA PROP TURBOPROP 0.61 GEARBOX 0.12 ADVANCED t TURBOPROP Figure 26. - Possible reductions in maintenance cost for propeller and gearbox. Unbroadened costs in 1976 dollars per flight hour.

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10- PROP GEARBOX FUEL W MAINTENANCE Cos T, o' COSTS 0LITER IQlgall N lt^ 8- ° Q BASELINE It^01 © DOUBLE z a LJ e-5 g lb t o < ► - 0 1 I w ^ z 4 W I, ;/ --I- - 0 -- LOCKHEED BOEING NAS2-8612 NAS2-9104 Fiqure 27. - Direct operatingcost sensitivity to propeller and gearbox maintenancecosts.

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_ T ^ I ` 1 J SAVINGS RHAT1VE TO CURRENT ENGINES 40 r-- 1 ADVANCED ^^11,1 TURBOPROPS

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Ii Wt a 20 ///// f ENERGY EFFICIENT W ENGINE 1 0 l ENGINE COMPONENT IMPROVEMENT 0 5 10 15 20 i DOC SAVINGS, `70 Fiqure 28. - Potential benefits of ACEE propulsion projects.

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• I • I Hot. " ? .{uenl't Catalog Ni, No 7 Government Acca•t•on No N•c NASA TM- 78962 1: 4 Tdie and SutAdie b Ne{M»t Data 1UFL CONSERVATIVE: AIRCRAFT ENGINE TECHNOLOGY Perform.nq 01gan.titron Code • fi N Pph»mop nrganNhcM Ne{r»1 Nu .- 1 Autltorltl E-9719 Donald L. Nored 10 Wr»• Un.l No `^^ 4 Prltorm-nycNgamrahon Name and Addrrt+ National Aeronautics and Since Administration 11 C•ontrut or Gant No Lewis Research Center Cleveland, Ohio 44135 17 Type of MOMWt and Period C,o yered ne an,1 Addrett I l Sp unsor mg AW * Na • .1'echnical Memorandum National Aeronautics aril Space Administration lA Sj,o-".ng Agency Grde t Washington, D.C. 20546 15 Srpplenwntary Notes 1 ` 4b{trui i -t wr new thrust in NASA's aeronautical r esearch is the Aircraft Energv Efficiency Program, ;1is program, initiated in an effort to minim ► , a the adverse impact of the world wide fuel crisis T on the aviation industry, will develr.p technology for more fuel-efficiency subsonic transport aircraft. It includes three major propulsion projects- (1) Engine Component Improvement - directed at current engines, (2) Energy Efficient Engine - directed at new turix1fan engines, and I (3) Advanced Turhoprops - directed at technology for advanced turtx,prop-Ix)wered aircraft.

This paper reviews each proje^t, describes some of the technologies and recent accomplishments, and summarizes their respectiv? status.

17 Key Words (Suggested by Authw1s)1 18 Distribution Statement AC'EE; Energy efficient engine; Turboprop; Unclassified - unlimited Turbofan component improvement STAR Category 07 urity Clagil (of 1h,% pays' Prn r ,— 19 Set urHy CI•uil (of chit reporU JO Sec ! 1 Nu of Papr• ^ JJ Unclassified Unclassified For sale by the National Technical information Servlc• Spnnphekl VIrpu11a 22161 ,1 w_