Comparison of Sound Emission from Two-Blade, Four-Blade, and Seven-Blade Propellers

Abstract

Appreciable sound-pressure reduction may be realized by changing from two blades to seven blades for comparable operating conditions. Small reduction in intensity may be realized by increasing propeller diameter for same tip speed and power absorbed. AT fixed pitch setting, sound-intensity levels expressed in decibels are approximately a linear function of tip speed for test Mach number range for all propellers tested. For same tip speed and power absorbed, seven blades are only slightly less loud than two blades at distances greater than 400 ft even though difference in sound pressure is large.

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Document Details

Document Type
Technical Report
Publication Date
Jul 01, 1947
Accession Number
ADA801336

Entities

People

  • Chester W. Hicks
  • Harvey H. Hubbard

Organizations

  • National Advisory Committee for Aeronautics

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Absorption
  • Aircrafts
  • Atmospheric Attenuation
  • Diameters
  • Emission
  • Engineering
  • Frequency
  • Helicopter Rotors
  • Intensity
  • Mach Number
  • Measurement
  • Propeller Blades
  • Propeller Noise
  • Propellers
  • Sound Pressure
  • Wave Analyzers
  • Waves

Readers

  • Acoustics.
  • Aerodynamics.