Turbofan

About: Turbofan is a research topic. Over the lifetime, 4114 publications have been published within this topic receiving 39490 citations. The topic is also known as: fanjet & turbofan engine.

Numerical modeling of three-dimensional flows in turbofan engine exhaust nozzles

Abstract: An experimental and numerical study was conducted to investigate the use of three-dimensi onal viscous analysis for the design of internal mixers for jet noise suppression. Three flows, a full-scale free mixer, a fullscale lobed mixer, and a model-scale lobed mixer, were selected for study. Details of the experiments, turbulence modeling, and the determination of initial flow properties from engine operating properties are described together with a discussion of the usefulness of the analysis for mixing design. Overall the results are encouraging and, at least for the flows considered here, numerical analysis appears to compare favorably with model-scale tests as a simulation of the full-scale flow.

Area ruled nacelle

Abstract: An aircraft powered by a turbofan gas turbine engine is provided with an aircraft/engine installation in which either the nacelle which surrounds the fan or the core engine nacelle is area ruled to give a flow relief in the region of the wing pylon which extends into the fan passageway. The flow relief reduces the local static pressure upstream of the pylon and thus eliminates the distortion effects on the fan thereby increasing installed thrust and also reducing interference drag. The same area rule principle is also applied to regions of the fan passageway upstream of any obstruction, such as an engine control or accessory mounted on the core engine casing.

A study to define the research and technology requirements for advanced turbo/propfan transport aircraft

Abstract: The feasibility of the propfan relative to the turbofan is summarized, using the Douglas DC-9 Super 80 (DS-8000) as the actual operational base aircraft. The 155 passenger economy class aircraft (31,775 lb 14,413 kg payload), cruise Mach at 0.80 at 31,000 ft (8,450 m) initial altitude, and an operational capability in 1985 was considered. Three propfan arrangements, wing mounted, conventional horizontal tail aft mounted, and aft fuselage pylon mounted are selected for comparison with the DC-9 Super 80 P&WA JT8D-209 turbofan powered aircraft. The configuration feasibility, aerodynamics, propulsion, structural loads, structural dynamics, sonic fatigue, acoustics, weight maintainability, performance, rough order of magnitude economics, and airline coordination are examined. The effects of alternate cruise Mach number, mission stage lengths, and propfan design characteristics are considered. Recommendations for further study, ground testing, and flight testing are included.

Integral infrared radiation suppressor for a turbofan engine

Abstract: Apparatus is disclosed for minimizing the infrared radiation emitted at the aft end of a bypass fan type turbine engine. Minimization is accomplished by ducting cool air from the secondary bypass airstream through an annulus to form a sheath of cooler air around the gas stream as it is discharged from the engine tailpipe. The sheath of air educted along the inside surface of the engine tailpipe minimizes infrared radiation in two ways. First it reduces the operating temperature of the tailpipe thus keeping radiation therefrom to a low level. Second, the cool outside air becomes entrained in the hot gas stream discharged from the turbine. This results in a reduction of the effective temperature of the gas plume and suppresses infrared radiation therefrom.

Thrust reverser nozzle

Abstract: A thrust reverser nozzle for coaxial-flow turbofan engines comprising target-type deflector doors which are hinged for deployment about a fixed axis by means of actuation about single fixed pivots mounted on support structure on either side of the engine nacelle rearward portion. The deflector door's outer surfaces are shaped to match existing aerodynamic contours of the aircraft engine nacelle so as to provide a lower boattail angle for improved drag characteristics in the stowed or normal flight position. In that position, the deflector door interior configuration comprises a portion upstream of the engine exhaust nozzle exit plane and a downstream "fishmouth" portion through which flows hot engine exhaust gases surrounded circumferentially by cool air discharged from the engine fan. Geometry of the stowed fishmouth is sized and shaped to take advantage of mixing and shearing action between the exhaust streams so as to produce a desired variable area nozzle effect on the engine operation and thereby improve its forward thrust performance. Geometry of the upstream portion of the inside surface of the doors is sized and shaped with end plates so that when the deflector doors move to the deployed position, the exhaust streams are diverted outward and forward to produce a desired level of reverse thrust.