Military Aircraft Engine Accessories

1984 ◽  
Vol 56 (6) ◽  
pp. 2-4
Author(s):  
M.M. Leonard
Keyword(s):  
Aircraft Engine ◽  
Military Aircraft

Nozzle dimension design for aircraft engine infrared signature and thrust active control using MOEA/D

2020 ◽  
Vol 234 (15) ◽  
pp. 2133-2138
Author(s):  
Yu Zhao ◽  
Shijie Zheng
Keyword(s):  
Nozzle Exit ◽  
Infrared Radiation ◽  
Exhaust System ◽  
Aircraft Engine ◽  
Radiation Energy ◽  
Diameter Ratio ◽  
Rear Side ◽  
Military Aircraft ◽  
Infrared Signature ◽  
Aircraft Survivability

Aircraft infrared signature is one of the most important properties for the military aircraft survivability. In terms of military aircraft, the exhaust system is the most significant infrared radiation source. The exhaust system accounts for more than 90% of the aircraft infrared radiation, and that the exhaust nozzle contributes the most significant infrared radiation of the whole radiation energy provided by the exhaust system from the rear aspect. Low detectionable feature for military aircraft has attracted more importance to promote aircraft survivability via reducing infrared signature. The alteration of nozzle exit area affects an aircraft engine performance; meanwhile, it severely influences the engine infrared signature radiation from the rear side. The present paper is mainly focused on searching an appropriate group of nozzle exit diameter and throat to exit diameter ratio, which can reduce infrared signature radiation while cutting down the loss of thrust. Hence, objectives involve two aspects: one is minimum infrared signature level, and the other is minimum thrust loss. The multi-objective evolutionary algorithm based on decomposition has been employed to solve this bi-objective optimization problem. The optimization results illustrate that dimension selection range and throat to exit diameter ratio exert more important effect on the thrust loss and infrared signature level. Furthermore, the thrust plays significant role for deciding nozzle exit diameter and throat diameter.

Laser Peening Technology for Remote Processing of Pressure Vessels

2005 ◽  
Author(s):  
Lloyd A. Hackel ◽  
C. Brent Dane ◽  
Jon Rankin ◽  
Fritz Harris
Keyword(s):  
Critical Stress ◽  
High Performance ◽  
Aircraft Engine ◽  
Pressure Vessels ◽  
Metal Alloys ◽  
Complex Geometries ◽  
Laser Peening ◽  
Jet Engines ◽  
Military Aircraft ◽  
Large Pressure

Laser peening technology has matured into a fully qualified production process that is now in routine and reliable use for a broad range of metal alloys. Deep compressive stress developed in metal surfaces extends the fatigue life and stress corrosion cracking life of components, and will enable designers to consider higher stress levels in certain life limited designs. This technology has been applied to critical stress areas of military aircraft engine fan blades and to over 12,000 wide cord fan blades and blade hubs for operation in high performance commercial jet engines. A broad range of materials are in production or development, including but not limited to Ti 6/4 (alpha and beta and BSTOA), 300M and 9310 steels, A1 7050, and A1 2023. Enhancement to the life of components with complex geometries and welds has been demonstrated. The processing capability is being extended with the introduction of a transportable laser peening system including a moveable beam that can go out in the field to treat large pressure vessel systems allowing applications not previously possible.

A Reliable Spline Coupling

1979 ◽  
Vol 101 (4) ◽  
pp. 421-426 ◽  
Author(s):  
H. W. Brown
Keyword(s):  
Aircraft Engine ◽  
Design Development ◽  
Military Aircraft ◽  
Commercial Aircraft ◽  
Mean Time Between Failures ◽  
Time Between Failures ◽  
Spline Coupling ◽  
Special Concern ◽  
Mean Time ◽  
Involute Spline

Involute spline couplings are commonly used in aircraft to transmit power to gearboxes, generators, pumps, and other engine driven accessories. Spline driven accessories which are cantilever mounted on an aircraft engine are of special concern to the user as these interface splines characteristically exhibit extremely poor reliability. To compound the problem, replacement of splines is difficult and costly due to their inaccessibility. Whereas the engine driven accessory may demonstrate a mean time between failures (MTBF) of 2000 hr., the spline coupling typically fails within 500 hr. Consequently, the degree of maintenance demanded by spline wear conflicts with the operational requirements of military or commercial aircraft. Failures can also compromise flight safety. This paper reviews recent spline research directed at understanding the characteristics and problems of conventional involute splines. It also discusses the design, development, and application of the circular spline coupling (MS14169) which was developed to solve spline wear problems being experienced in military aircraft.

Trends in Military Aircraft Propulsion

1989 ◽  
Vol 203 (1) ◽  
pp. 11-23
Author(s):  
R M Denning ◽  
N A Mitchell
Keyword(s):  
Aircraft Engine ◽  
Development Programme ◽  
Military Aircraft ◽  
Engine Design ◽  
Combat Aircraft ◽  
Major Parameter ◽  
Specific Thrust ◽  
Major Factors ◽  
Vertical Landing ◽  
Engine Cycle

The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design. Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics. The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed. Experience shows that the technology for these advanced engines must be fully demonstrated before production to minimize the risks and costs of the development programme.

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