Engine noise reduction research currently underway in the NASA Advanced Subsonic Technology Noise Reduction Program is described. Emphasis is on noise reduction technology for high to ultra-high bypass ratio turbofan engines which will dominate the airline fleets early in the 21st century. In terms of noise components, primary emphasis is on the fan with secondary effort on the jet for engines at the lower end of the bypass ratio range. The approach to fan noise prediction considts of modeling the chain of physical processes beginning with flow disturbances on fan blades and ending with far field sound levels. For the jet, CFD solutions for the nozzle geometries are coupled to combined aeroacoustic source/radiation models. On the experimental side, realistic models of fans, nacelles, and nozzles are tested in aeroacoustic wind tunnels. Comparisons of predicted and measured noise levels are presented as indicators of progress toward developing improved low-noise design tools. The challenges of applying active control concepts to turbofan noise are discussed including both cancellation and source modification approaches.
Advanced subsonic aircraft engine noise reduction research
Untersuchung der Geräuschminderung bei einem fortschrittlichen subsonischen Flugzeugantrieb
1996
6 Seiten, 6 Bilder, 15 Quellen
Aufsatz (Konferenz)
Englisch
Subsonic transport aircraft engine noise
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