Power plants – Reaction motor – Air passage bypasses combustion chamber
Patent
1976-04-16
1978-03-07
Garrett, Robert E.
Power plants
Reaction motor
Air passage bypasses combustion chamber
60264, 2391273, 23926517, 181220, F02K 1102
Patent
active
040772063
ABSTRACT:
A low noise mixer apparatus for mixing the turbine exhaust effluent of a turbofan gas turbine engine with a portion of the air flowing from the engine fan stage prior to discharge from the engine is disclosed. The mixer is of the daisy variety, having a tubular mixer section that includes a number of axially extending, circumferentially spaced lobes with the tubular mixer section coaxially mounted around the engine plug. An outer duct coaxially surrounds the plug and mixer section. The turbine exhaust flows through an annular passage formed between the exterior surface of the plug and the interior wall of the mixer section and the fan air flows through an annular passage formed between the inner surface of the outer duct and the outer surface of the mixer section. As in previous daisy type mixers, the turbine exhaust and fan air are mixed as the two gaseous streams flow past the exit plane of the mixer section to thereby increase the thrust produced by the engine and also decrease the component of noise known as jet noise. To further reduce the overall engine noise level, the mixer of this invention includes a first acoustically absorbent material mounted along the crests of the axially extending mixer lobes and a second acoustically absorbent material axially mounted in the interlobal regions. The first acoustic material is selected to dissipate low frequency noise energy associated with the turbine exhaust gases (commonly called core noise) and the cross-sectional geometry of the mixer lobes are established to match the impedance of the first acoustically absorbent material to the characteristic impedance of the core noise traveling through the mixer. The second acoustically absorbent material is selected to dissipate the higher frequency noise associated with the flowing fan air. Advantageously, shaping the lobes for the impedance matching of the core noise to the impedance of the first acoustic material also tends to match the impedance of the second acoustic material to the impedance of the fan noise.
REFERENCES:
patent: 2426833 (1947-09-01), Lloyd
patent: 3436020 (1969-04-01), Duthion et al.
patent: 3467312 (1969-09-01), Mehr
patent: 3481427 (1969-12-01), Dobbs et al.
patent: 3583640 (1971-06-01), MacDonald
patent: 3730292 (1973-05-01), MacDonald
patent: 3861140 (1975-01-01), Krabacher
Garrett Robert E.
The Boeing Company
LandOfFree
Gas turbine mixer apparatus for suppressing engine core noise an does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas turbine mixer apparatus for suppressing engine core noise an, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas turbine mixer apparatus for suppressing engine core noise an will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2015183