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.

Turbofan gas turbine engine aerodynamic mixer

Abstract: A mixer for a turbofan engine (100) includes a centerbody (144) and a mixer nozzle (146). The mixer nozzle (146) surrounds at least a portion of the centerbody (144) and is spaced apart to define a core flow path between the mixer nozzle (146) and the centerbody (144). The mixer nozzle (146) is configured, when bypass air flows through the turbofan engine (100), to direct at least a portion of the bypass air to impinge on the centerbody (144). The mixer nozzle (146) includes a plurality of circumferentially spaced mixer lobes (206) that extend axially in a rearward direction and have a cross-section shape defined by a set of equations.

Advanced Turbofan Duct Liner Concepts

Abstract: The Advanced Subsonic Technology Noise Reduction Program goal is to reduce aircraft noise by 10 EPNdB by the year 2000, relative to 1992 technology. The improvement goal for nacelle attenuation is 25 percent relative to 1992 technology by 1997 and 50 percent by 2000. The Advanced Turbofan Duct Liner Concepts Task work by Boeing presented in this document was in support of these goals. The basis for the technical approach was a Boeing study conducted in 1993-94 under NASA/FAA contract NAS1-19349, Task 6, investigating broadband acoustic liner concepts. As a result of this work, it was recommended that linear double layer, linear and perforate triple layer, parallel element, and bulk absorber liners be further investigated to improve nacelle attenuations. NASA LaRC also suggested that "adaptive" liner concepts that would allow "in-situ" acoustic impedance control also be considered. As a result, bias flow and high-temperature liner concepts were also added to the investigation. The major conclusion from the above studies is that improvements in nacelle liner average acoustic impedance characteristics alone will not result in 25 percent increased nacelle noise reduction realtive to 1992 technology. Nacelle design advancements currently being developed by Boeing are expected to add 20-40 percent more acoustic lining to hardwall regions in current inlets, which is predicted to result in and additional 40-80 percent attenuation improvement. Similar advancements are expected to allow 10-30 percent more acoustic lining in current fan ducts with 10-30 percent more attenuation expected. In addition, Boeing is currently developing a scarf inlet concept which is expected to give an additional 40-80 percent attenuation improvement for equivalent lining areas.

Internal Mixing Of A Portion Of Fan Exhaust Flow And Full Core Exhaust Flow In Aircraft Turbofan Engines

Abstract: An integrated, single piece mixer-center body ventilation apparatus is disclosed for use with a turbofan jet engine. The apparatus may incorporate a circumferential forward body portion adapted to be coupled to an aft end of a core engine turbine case of the jet engine, and a center body tube portion integrally formed with the forward body portion and having an axially opening vent exit. The forward body portion may have a plurality of inner mixer flow paths in communication with scalloped projecting portions. The inner mixer flow paths direct a pressurized core exhaust flow through the mixer device and mix the pressurized core exhaust flow with a portion of a pressurized fan exhaust flow, to thus significantly cool the pressurized core exhaust flow.

Turbofan engine with a low pressure turbine driven supercharger in a bypass duct operated by a fuel rich combustor and an afterburner

Abstract: A multiple bypass turbofan engine includes a core Brayton Cycle gas generator with a fuel rich burning combustor and is provided with a variable supercharged bypass duct around the gas generator with a supercharging means in the supercharged bypass duct powered by a turbine not mechanically connected to the gas generator. The engine further includes a low pressure turbine driven forward fan upstream and forward of an aft fan and drivingly connected to a low pressure turbine by a low pressure shaft, the low pressure turbine being aft of and in serial flow communication with the core gas generator. A fan bypass duct is disposed radially outward of the core engine assembly and has first and second inlets disposed between the forward and aft fans. An inlet duct having an annular duct wall is disposed radially inward of the bypass duct and connects the second inlet to the bypass duct. A supercharger means for compressing air is drivingly connected to the low pressure turbine and is disposed in the inlet duct. A secondary combustor or augmentor is disposed in an exhaust duct downstream of and in fluid flow communication with the bypass duct and the gas generator.