Aircraft Propulsion Systems Research Articles

Laser Machining of Aero Engine Components

EVER increasing demand for high efficiencies from aircraft propulsion systems drives designers to continue to strive for the improved thermodynamic efficiencies attainable only by operating at ever higher absolute temperatures. In addition to significant developments in the materials used in the last two decades, engine components must be protected by forced cooling and boundary layer control strategies. Large numbers of accurately sized and positioned small holes are essential to direct cooling air to precise positions in accurately metered amounts.

低騒音ＳＴＯＬ実験機の推進システムについて

低騒音ＳＴＯＬ実験機の推進システムについて

Propulsion Systems For Rotary Wing Aircraft with Auxiliary Propulsors

Propulsion Systems For Rotary Wing Aircraft with Auxiliary Propulsors

Ion Implanting Bearing Surfaces for Corrosion Resistance

A program is currently underway to use ion implantation to improve the tribological and corrosion characteristics of load bearing surfaces in both rolling element bearings and gears used in aircraft propulsion systems. This paper describes that aspect of the program concerned with the use of ion implantation for surface alloying of bearing components in order to alleviate the problem of corrosion in costly M50 steel mainshaft aircraft engine bearings. Results to data indicate that implantation of selected ion species can significantly improve resistance to both generalized and localized (pitting) corrosion without adversely affecting bearing performance or fatigue endurance life.

Propulsion systems for civil transport aircraft

The aero engine has developed from the piston engine and propeller through the pure jet turbine and high bypass turbofan to a possible re-emergence of the advanced turbopropeller engine. The author traces the evolution of propulsion systems for civil transport aircraft and suggests how fuel efficiency could be improved

Design and Performance of the Propulsion System for the Quiet Short-Haul Research Aircraft

This paper describes the design and performance of the Quiet Short-Haul Research Aircraft (QSRA) propulsion system. A discussion of the mixed-flow boundary layer control (BLC) system, which uses high and low pressure engine bleed air, is included. This system seriously affected propulsion system performance, particularly engine acceleration characteristics, requiring an integration of BLC system and powerplant controls. Funding limitations for the QSRA Project prevented extensive full-scale testing and systems mockups, resulting in a high reliance on small-scale tests and analytical techniques. Ground tests of the actual aircraft systems showed that the extrapolation of small-scale tests and analytical techniques were in good agreement with measured full-scale results.

Wear of seal materials used in aircraft propulsion systems

The various types of seal locations in a gas turbine engine are described and the significance of wear for each type is reviewed. Starting with positive contact shaft seals, existing material selection guidelines are reviewed and the existing PV (contact pressure × sliding velocity) criteria for selecting seal materials are discussed together with the theoretical background for these criteria. Examples of wear mechanisms observed to operate in positive contact seals are shown. Design features that can extend the operating capabilities of positive contact seals, including pressure balancing and incorporation of hydrodynamic lift, are briefly discussed. It is concluded that, despite the benefits arising from these design features, improved positive contact seal materials from the standpoint of wear, erosion and oxidation resistance will be necessary for further improvements in seal performance and durability and to meet stringent future challenges. Materials used in noncontacting gas path seal applications are described and a review of wear studies performed on these materials is presented. Factors that promote drastic changes in the structure and wear behavior of highly porous gas path seal materials are discussed. A correlation between wear characteristics and a factor that includes material strength, ductility, specific heat and hotworking temperature is proposed for low porosity metallic gas path seal materials.

Normal Modes Vibration Analysis of the JT9D/747 Propulsion System

The results of an exploratory research program on structural integration of aircraft propulsion systems are reported. The need for cooperative analysis by the engine and airframe manufacturers is discussed. The procedures for executing a multicompany, integrated vibration analysis are described. An 11,000-degree-offreedom, finite-element model of the JT9D/747 installation was assembled and reduced to 388 freedoms from which 388 natural frequencies and 50 mode shapes were calculated. The model was evaluated by correlation with available test data.

Dynamic-stress-data management for aeromechanical testing of turbomachinery

Aeromechanical testing of turbine engines is an important benchmark in the development of today's modern aircraft propulsion systems, and detailed dynamic-strain gaging of the engine's compressor and turbine are required to provide insight to the integrity of these engine components. Comprehensive real-time visualization of the compressor/turbine dynamic stress is necessary for safe engine operation and rapid posttest data-editing/processing systems are essential for day-to-day test-program direction.

F-12 Series Aircraft Propulsion System Performance and Development

108, March 1972, Air Force Flight Dynamics Lab., Wright-Patterson Air Force Base, Ohio. Harder, R. L. and Rodden, W. P., Kernel Function for Nonplanar Oscillating Surfaces in Supersonic Flow, Journal of Aircraft, Vol. 8, No. 8, Aug. 1971, pp. 677-679. Cunningham, A. M., Jr., The Application of General Aerodynamic Lifting Surface Elements to Problems in Unsteady Transonic Flow, CR-112264, Feb. 1973, NASA. Multhopp, H., Methods for Calculating the Lift Distribution of Wings, (Appendix I, Contributed by W. Mangier), Rept. Aero-2353, January 1950, Royal Aircraft Establishment, Farnborough, Great Britain.

Investigation of Air Bearings for Small High-Performance Aircraft Gas Turbines

High temperatures and rotative speeds of future U. S. Army aircraft propulsion systems will impose increasingly severe operating requirements on oil-lubricated engine bearings and associated seals. Accordingly, air-lubricated bearings are being investigated as a possible approach to alleviating the lubrication problems. This paper presents the results of design and performance studies, as well as bearing component tests, relative to applying air bearings to a two-shaft, 3.5-lb/sec turboshaft engine. The test results verify that air bearings can carry the maximum loads imposed by flight and landing conditions, and can survive the sliding contacts associated with 15,000 engine start/stop cycles. Incentives for pursuing the air-bearing approach are identified, as are also the development and problem areas.

Operational Constraints for STOL Aircraft

The Short Takeoff and Landing (STOL) transportation system has been proposed as a solution to short-haul transportation congestion, because it 1) operates independently of the existing Conventional Takeoff and Landing (CTOL) system; 2) offers more convenience to short haul travelers; and 3) relieves congestion at major airports. However, the STOL transportation system encounters operational constraints which differ from current CTOL aircraft. These constraints are: economics, short-haul market characteristics, operating environment, and community acceptance. This paper discusses how these constraints influence the STOL aircraft's size, speed, propulsion system, takeoff/landing performance, and maneuverability.

Control of Noise Generated by Aircraft at Subsonic Speeds

Eight papers were given in the session on aircraft noise. These included a summary of the status of noise control for gas turbine engines and several detailed presentations on specific technical subjects. The summary included a discussion of the proven technology for reducing noise from various types of aircraft propulsion systems (Hubbard), a survey of trends in aircraft-engine noise control (Marsh), a detailed example of the application of the gain in noise-reduction technology of the 1960s to flight hardware of the future (Eldred), and an outline of the problems encountered in measuring aircraft noise (Zwieback). This summary was followed by a plea for greater noise reduction so that the ariport-community noise problem can have a national solution, and a projection of the effect of FAA noise certification and new technology on aircraft in the future (Odell). Specific technical subjects included the effect of segmented blades on fan noise (Embleton and Thiessen), the understanding of nearfield noise for high-speed subsonic jets (Maestrello and McDaid), and the response of panels to supersonic turbulence (Maestrello).

Month in the Patent Office

An aircraft propulsion system comprises two heat sources, one being a combustion apparatus and the other a nuclear reactor. The aircraft shown in FIG. 1 has two propulsion units and a single nuclear reactor 2, the latter being mounted in the fuselage and heating the working fluid of the two propulsion units indirectly by means of an auxiliary fluid such as liquid metal which is circulated through heat exchangers 8.

MARINE APPLICATION OF AIRCRAFT PROPULSION SYSTEMS

Journal of the American Society for Naval EngineersVolume 67, Issue 4 p. 933-944 MARINE APPLICATION OF AIRCRAFT PROPULSION SYSTEMS U. A. POURNARAS, U. A. POURNARAS THE AUTHOR: was born in Athens, Greece, received the degree of the Bachelor of Science in Naval Architecture and Marine Engineering from the Massachusetts Institute of Technology. He has been associated with the design offices of John G. Alden, and Hickman Sea-Sled Co., both of Boston, Mass., and is presently employed as a Naval Architect in the Hydromechanics Laboratory of the David W. Taylor Model Basin, USN, where he is associated with the Hydrofoil Research Program.Search for more papers by this author U. A. POURNARAS, U. A. POURNARAS THE AUTHOR: was born in Athens, Greece, received the degree of the Bachelor of Science in Naval Architecture and Marine Engineering from the Massachusetts Institute of Technology. He has been associated with the design offices of John G. Alden, and Hickman Sea-Sled Co., both of Boston, Mass., and is presently employed as a Naval Architect in the Hydromechanics Laboratory of the David W. Taylor Model Basin, USN, where he is associated with the Hydrofoil Research Program.Search for more papers by this author First published: November 1955 https://doi.org/10.1111/j.1559-3584.1955.tb03168.x AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume67, Issue4November 1955Pages 933-944 RelatedInformation