Accession Number:

AD0741778

Title:

Investigation of the Vortex Noise Produced by a Helicopter Rotor

Descriptive Note:

Final technical rept.

Corporate Author:

ROCHESTER APPLIED SCIENCE ASSOCIATES NY

Personal Author(s):

Report Date:

1972-02-01

Pagination or Media Count:

137.0

Abstract:

Karman-street-type vortex shedding from a lifting surface was analyzed as a source of noise from a helicopter rotor in hover and forward flight. Experimental pressure-time histories were analyzed, and high resolution spectra were developed over a frequency range of 0 to 5000 Hz using a 0.7-Hz filter. The results of the investigation indicated that vortex noise is the major source of acoustic radiation from a helicopter rotor in hover or low-speed flight and that it is concentrated in the frequency range of 200 to 500 Hz.

Subject Categories:

  • Helicopters
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE