Reduction of High-Speed Impulsive Noise by Blade Planform Modification of a Model Helicopter Rotor.

Abstract

An experiment has been performed to investigate the reduction of high-speed impulsive noise for the UH-1H helicopter by using an advanced main rotor system. The advanced rotor system had a tapered blade planform compared with the rectangular planform of the standard rotor system. Models of both the advanced main rotor system and the UH-1H standard main rotor system were tested at 1/4 scale in the Langley 4- by 7-Meter Tunnel. In-plane acoustic measurements of the high-speed impulsive noise demonstrated that the advanced rotor system on the UH-1H helicopter reduced the high-speed impulsive noise by up to 20 dB, with a reduction in overall sound pressure level of up to 6 dB. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1982
Accession Number
ADA123499

Entities

People

  • Danny R. Hoad
  • David A. Conner

Organizations

  • National Aeronautics and Space Administration

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Aircrafts
  • Background Noise
  • Band Spectra
  • Blade Tips
  • Data Reduction
  • Far Field
  • Free Stream
  • Frequency
  • Helicopters
  • Mach Number
  • Measurement
  • Microphones
  • Noise
  • Sound Pressure
  • Test Facilities
  • Transducers
  • Wind Tunnels

Fields of Study

  • Physics

Readers

  • Acoustics.
  • Aerodynamics.
  • Aerodynamics/Aeronautics.