Some measured and calculated effects of a tip vortex modification device on impulsive noiseThe results of a recent wind tunnel test program to evaluate the effectiveness of the Tip Air Mass Injection (TAMI) system in modifying the blade tip vortex occurring during helicopter flight is described with attention to the effect of this modification on the impulsive noise. The measurement program is explained, and the correlation between experimental and predicted results is discussed. Topics considered include the effect of descent rate on noise pressure time histories, the effect of air mass injection on noise, and the analysis based on a dB(A) weighted approach. Impulsive noise generated by the interaction of a helicopter rotor blade and the concentrated tip vortex during forward flight descent is a primary contributor to acoustic annoyance as it draws early attention to the presence of the helicopter.
Document ID
19770068242
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Pegg, R. J. (NASA Langley Research Center Hampton, Va., United States)
White, R. P., Jr. (Systems Research Laboratories, Inc. Newport News, Va., United States)
Date Acquired
August 9, 2013
Publication Date
October 1, 1977
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 77-1341
Meeting Information
Meeting: Aeroacoustics Conference
Location: Atlanta, GA
Start Date: October 3, 1977
End Date: October 5, 1977
Sponsors: American Institute of Aeronautics and Astronautics