Showing papers on "Turbofan published in 1968"

Theory and test of flow mixing for turbofan engines.

Abstract: For certain applications of advanced turbofan engines, it is advantageous to transport various amounts of the gas-producer kinetic energy to a second stream. The reasons for and the advantages and methods of gasdynamic energy transport (mixing process) are explained with different examples. The optimum layout of fan engines with and without mixing is discussed, and the influence of partial mixing on performance is pointed out. Theoretical considerations, which show that the thrust of bypass turbojet engines may be increased by mixing the hot exhaust jet with the cold bypass flow, are compared with experimental data. Tests of three mixer configurations were conducted on an experimental rig with very accurate thrust measurements and flow profile instrumentation at different sections of the mixing chamber. Results of these experiments are discussed.

Influence of high-turbine inlet temperature engines in a methane-fueled SST when takeoff jet noise limits are considered

Abstract: Afterburning turbojet, nonafterburning turbojet, and duct burning turbofan designs for supersonic transports with and without takeoff noise constraints

Augmentation systems for turbofan engines

Abstract: Summary The modern augmented turbofan engine is an attractive powerplant cycle for many advanced high performance applications. Augmentation of either the fan stream alone or both the fan and turbine exhaust streams may be desirable. In both cases, unique combustion problems are presented that are due primarily to the low temperature environment. At the flow conditions existing in the fan duct, stable efficient combustion is inhibited by poor fuel vaporization and distribution. In addition, advanced turbofan combustors must fulfil engine performance requirements that are beyond the range of previous experience. Typical augmentation requirements include high combustion efficiency, particularly for cruise vehicles, ignition at very lean fuel-air ratios, low pressure operation and thrust modulation over an unprecedented range. Combustor pressure losses are detrimental to advanced turbine cycle performance and must be kept to a minimum. The requirement for low pressure loss is at cross purposes with that for stable operation and creates a fundamental problem in duct heater development. An additional problem is created by the heterogeneous character of the fuel-air mixture which curbs the thrust potential of both duct heaters and common afterburners. In the case of common afterburners, in particular, residence times for combustion are reduced by the demand for shorter lengths and by higher duct Mach numbers. To arrive at potential solutions to the above problems and to evolve combustor designs suitable for further development, experimental combustion programs have been conducted. At typical duct heater operating conditions (inlet air temperatures as low as 100°F), conventional bluff body stabilizers, piloted can combustors and aerodynamic flameholding techniques have been evaluated. Aerodynamic and combustion performance data are presented for these devices and their limitations and potential use are discussed. Similar experiments were conducted at mixed flow afterburning conditions where emphasis was placed upon utilizing available energy in the turbine exhaust to promote stable efficient operation in the cold fan portion of the stream. Mixing data are also presented to show the effect on aerodynamic performance.

The Rolls‐Royce Three Shaft Turbofan Engine: A detailed examination of the new family of advanced technology engines under development by Rolls‐Royce Ltd.

Abstract: IT is nearly fifteen years since the introduction into civil operations of the Dart turboprop in the Vickers Viscount and the Ghost turbojet in the dc Havilland Comet. For many years it was thought that the turboprop would remain dominant in the short and medium haul classes, but the continued demand for higher cruising speeds and the passenger appeal of the jet have been largely responsible for the turboprop aircraft being superseded by the new generation of turbofan aircraft.

Variability in airplane noise measurements

Abstract: Aircraft position and meteorological effects on accuracy of acoustic measurements for turbojet engines

V/STOL Employing ARL Thrust Augmentation Concepts - Research Test Vehicle Configuration Summary and Design Technology Report.

Abstract: : The results of a detailed preliminary design study of a V/STOL research test vehicle (RTV), employing ARL thrust augmentation concepts, are presented. The V/STOL research airplane uses a high by-pass ratio turbofan engine with ejector thrust augmentation in the wing and fuselage nose. Design layouts of all major configuration components and systems are presented together with results of analytical investigations and trade-off studies.

Water-Augmented Turbofan Engine

Abstract: This paper describes a novel lightweight propulsion scheme for use in high-speed ships in which large amounts of water are injected into the fan discharge duct of an aircraft- type turbofan engine. Theoretical design and off-design performance for this water-augmented turbofan engine show that dry thrust theoretically can be augmented 380% at 25 knots and 90% at 100 knots. The reduction in theoretical performance caused by nonoptimum rates of water injection and by two- phase flow losses is not sufficient to detract from significant thrust augmentation. The results show that in many marine vehicle applications the slightly lower propulsive efficiency of the water-augmented turbofan engine, relative to more conventional propulsion systems, is more than compensated for by its extremely low system weight.

Turbojet and turbofan cycle considerations and engine configurations for application in lightweight aircraft

Abstract: Cycle characteristics and structural configuration of turbojet and turbofan engines for lightweight aircraft

Quiet engine program preliminary engine design and aircraft integration

Abstract: Design considerations for integration of turbofan engine with reduced noise output in jet aircraft