The influence of quadrupole sources in the boundary layer and wake of a blade on helicopter rotor noiseIt is presently noted that, for an observer in or near the plane containing a helicopter rotor disk, and in the far field, part of the volume quadrupole sources, and the blade and wake surface quadrupole sources, completely cancel out. This suggests a novel quadrupole source description for the Ffowcs Williams-Hawkings equation which retain quadrupoles with axes parallel to the rotor disk; in this case, the volume and shock surface sourse terms are dominant.
Document ID
19930045413
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Farassat, F. (NASA Langley Research Center Hampton, VA, United States)
Brentner, Kenneth S. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1991
Publication Information
Publication: In: AHS and Royal Aeronautical Society, Technical Specialists' Meeting on Rotorcraft Acoustics(Fluid Dynamics, Philadelphia, PA, Oct. 15-17, 1991, Proceedings (A93-29401 10-71)