N O T I C E This Document Has Been Reproduced From
Total Page：16
File Type：pdf, Size：1020Kb
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 I 4 NASA Technical Memorandum 82788 NASA Research Activities in Aeropropuision N82-1bQE4 (Na,A-TM- m ,!7db ) NASA HESkAHCH A ,-T1V1T1kJ IN AEKOPRUNUL:iION j4ASA) 30 p HC A03 /Mr A01 CSCL 11L UUC138 G3/07 U88U5 John F. McCarthy, Jr. and Richard J. Weber Lewis Research Center Cleveland, Ohio ok- Prepared for the Twenty-fourth Israel Annual Conference on Aviation 8n(,' Astronautics Tel Aviv, Israel, February 17-18, 1982 t 4 ^6 1r X031 w tic.tiN, od` RV%SA ^ NASA RESEARCH AL'TIVITIES IN AEROPROPOLSION John F. McCarthy, Jr.* and Richard J. Weber National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio U.S.A. Abstract located in Cleveland,,Ohio, on the shore of We Erie, is responsible for aeropropulsion (as well NASA is a civilian agency of the U.S. govern- as related ground and space power). As shown in ment, responsible for advancing technologies re- the aerial photograph of Fig. 3, this is a very lated to air transportation. This paper describes substantial installation. The replacement value a sampling of the work at NASA's Lewis Research of our facilities is over 1-1/2 billion dollars; Center aimed at improved aircraft propulsion sys- our staff of 2700 engineers, scientists, and sup- W tems. Particularly stressed are efforts related port personnel has an annual research budget for to reduced noise and fuel consumption of subsonic aeropropulsion of about 125 million dollars. transports. Generic work in specific disciplines Some of our major test facilities are large, high- are reviewed including computational analysis, altitude engine test chambers (Fig. 4), several materials, structures, controls, diagnostics, Dirge subsonic and supersonic wind tunnels that alternative fuels, and high-speed propellers. can operate continuously with a running engine Prospects for variable-cycle engines are also within them (Figs. 5 and 6), and noise teat stands discussed. (Fig. 7). Introduction Systems Technology Progress in aviation, dating from the Wright The focused research activities at NASA/Lewis brothers on through today, has been largely paced address the specific needs of all of the major by the performance of the propulsion system. classes of aircraft (Fig. 8). Rather than attempt This paper will describe the role of the National to discuss our work in all categories, this sec- Aeronautics and Space Administration (NASA) and tion will concentrate on the subject of subsonic its efforts toward improved powerplants. transports as an example, with only brief mention NASA vp S established as an independent, later of some other classes. civilian, government agency in 1958, charged by The principal concerns related to large com- Congress with the responsibility for advancing the mercial transports in recent years have been in technologieF necessary for improved air transpor- the areas of environmental acceptability and fuel tation (in addition to the space activities that consumption (Fig. 9). The problem of exhaust are more popularly recognized), Actually our emissions eventually was recognized to be rather aeronautics role is an uninterrupted continuation minor relative to other, non-aircraft pollution of the work of our predecessor agency, the sources, and diminished in public awareness once National Advisory Committee for Aeronautics new combustor technolog y eliminated visible (NACA), which dates back to 1915. smoke. However, the noise and fuel problems are In contrast to our space activities, where not so easily solved. NASA is an operating agency that actually procures and controls space vehicles, our aeronautics re- Noise Reduction sponsibilities are much more limited. Through a combination of research conducted within our own Anyone who lives or works near e, large air- facilities plus contracts with industry or univer- port is very conscious of the airplane noise prob- sities, we attempt to make available the techno- lem. Airport neighbors are becoming increasingly logies that will be required for safer and more sensitive and militant about the intrustion of efficient aircraft. Emphasis is placed on the noise into their lives. In response, more and long-term, high-risk topics that industry is not more airports are be-.n!& forced to limit the un- able to undertake on its own. As a program ap- constrained use. of their facilities. As shown in proaches the point of technical readiness, we Fig. 10, over a ten-year period the number of air- withdraw, leaving it to private companies to carry ports that impose some type of operational con- out product design, development, and production. straint (e.g., preferential runways or flight Within the specific area of propulsion our paths) hAs doubled, Additionally there has been a efforts are organized into two parallel, mutually striking increase in the imposition of out-right supportive categories (Fig, 1); (1) a broad, on- curfews. going generic research program in engine compo It is fortunate that technology has been able nents, overall systems problems, and related basic to offer some major reductions in engine source sciences, and (2) a focused program that responds noise over the years to help alleviate this prob- to the specific needs and characteristics of par- lem (Fig. 10. 1 The early turbojet engines were ticular vehicle types. Examples of both cate- extremely noisy. Introduction of the first- gories will be described in this paper. generation low-bypass-turbofans (JT3D, JT8D) and NASA's aeronautical rea•larch is conducted the moire-recent high-bypass-ratio engines (JT9D, through a number of laboratories or field centers CF6, RB 211) substantially reduced the tore ex- that ,re dispersed around the United States haust velocity and the associated jet noise. How- (Fig. %;), Of these, the Lewis Research Center, ever, the fan generated a new source of noise, and only strenuous efforts in fan machinery noise sup- *Director, Lewis Research Center. pression (e.g., blade spacing, reduced tip speed, wail treatment) have permitted the total noise to 0 Trenched compressor - an abradable mh;te- decrease as shown. rial is applied to the compressor casing Nnd is cut away or notched by the tips Fuel Consumption of the blades, so that running clear- ances are reduced and tip losses The fuel normally constitutes the single minimized. heaviest portion of a long-range airplane. Con- Stang fairing - the covering over the sequently the performance of the airplane is very thrust reverser mechanism is redesigned sensitive to engine fuel consumption, and reduc- to creata less aerodynamic drag. tion in this parameter has always been a goal of Turbine ACC - active clearance control the engine designer. Thus, very substantial im- reduce tip clearances provements in specific fuel consumption have been Turbine roundness - improved mechanical accomplished during the thirty years of commercial design and material selection reduces jet flight (Fig. 12). However, a new stimulus case distortion during throttle toward a more energy-efficient engine arose in the transients 1970'x. The 1973 oil embargo awoke still- continuing concern about the long-term avail- Energy efficient engine. - The effort ability of petroleum-based fuel. And, even when directed toward an entirely new, advanced turbofan available, a ten-fold cost increase (Fig. 13) has io known as the E 3 program. It, too, is prin- greatly increased the operating cost of aircraft cipally a contracted activity with PfiW and GE, and threatened the survival of many si+;lines. with in-house research support to help advance the The NASA response to this crisis, vtarting necessary component technologies. After an ini- in the mid-1970's, had three principal *1ements tial period of analysis and component work, this (Fig. 10. 2 First was a near-term effort to program is now entering a phase of large-scale relieve the immediate problem through modest hardware experimentation and technology valida- improvements in the existing fleet of engines; a tion. The E 3 goals (top of Fig. 16) in fuel five-percent saving in fuel consumption was the saving, economy, and environmental acceptability goal here. Second was an all-new engine design, thus far seem to be achievable. The sources of incorporating advanced technologies that would be the fuel benefit are indicated at the bottom of available in the mid-1980'x, with a potential fuel the figure. Discrete component improvements are saving of as much as 18 percent. The third cle- the major contributor. A more advanced cycle ment was a search for unconventional. still- (.higher pressure ratio and bypass ratio) is impor- longer-term concepts, that might be suv- antially tant, and is feasible largely because of those better than even the advanced turbofan. The re- same component advances. Forced mixing of the sult of this search was the advanced turboprop, core and bypass streams is another significant with a potential fuel saving of more than factor. 30 percent, The two E 3 designs are rasher similar. Engine component improvement (ECI) program. - Both have on overall pressure xatio '%OPR) of about The ECI program was performed throng~ contracts 37 and a bypass ratio (BPR) of nearly 7. The with Pratt b Whitney Aircraft Company and the maximum turbine inlet temperature at sea-level General Electric Compan , who manufacture the bulk takeoff (T, SLTO) is 100°-200° F higher than in of the engines in the present U.S. commercial today's engines. An example of the aggressive fleet. This program is now completed and resulted component technology is GE's compressor pressure in identifying practical means for improving the ratio of 23 in only 10 stages, with a polytropLc three major engines in current service by 4-6 per- efficiency of over 90 percent.