Surface Radiation Integrals in Aerodynamic Sound.

Abstract

Equations are derived for the contribution to far field acoustic pressure from sources distributed on a rotating and translating rigid surface, and from shock waves carried by the surface. Radiation integrals are expressed in coordinates fixed relative to the accelerating surface. The main results are an extension of the generalized surface-fixed Lowson formulation of the aerodynamic sound problem as derived by Ffowcs William and Hawkings in 1968. The general formulation is intended for application to the problem of calculating the sound field from a helicopter rotor blade with transonic conditions in the blade tip region. The sound field therefore includes contributions from non-compact source distributions on the blade surface and shock waves. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1974
Accession Number
ADA031126

Entities

People

  • Morris P. Isom

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Blade Tips
  • Blades
  • Differential Geometry
  • Equations
  • Far Field
  • Geometry
  • Helicopter Rotors
  • Helicopters
  • Integrals
  • Mach Number
  • Near Field
  • Pressure Distribution
  • Radiation
  • Shock
  • Shock Waves
  • Waves

Fields of Study

  • Physics

Readers

  • Acoustics.
  • Aerodynamics.
  • Calculus or Mathematical Analysis