The Aeroacoustics of Trailing Edges

  • William K. Blake
  • Jonathan L. Gershfeld
Part of the Lecture Notes in Engineering book series (LNENG, volume 46)

Abstract

Trailing edge sound is an aeroacoustic phenomenon which contributes to the noise from lifting surface flaps, rotating machines and certain turbulent nozzle flows. Part I of this paper is a survey which describes the physics of aerodynamic sound generation by trailing edge flows; it is particularly relevant to lifting surfaces. The survey will describe the importance of the geometry of the surface, its upstream boundary layer, and its trailing edge wake in determining the nature of the aeroacoustic sources. Techniques for measurement will be discussed and recent results will be brought forth which will further elucidate the relevant features of flow structure. Part 2 of the paper will deal with the trailing edge flow sources in more depth. A distinction is to be made between continuous-spectrum surface pressures that are locally generated by the immediate separated flow and narrower band pressures which are developed by superimposed orderly structures developing in the wake. The paper will also examine this distinction as well as the relevance of existing analytical models of trailing edge sound to each mechanism, and it will compare those theories to measurements of the sound generated by the separated trailing edge flow. General agreement is found between measurement and theory for both tonal and random aerodynamic sound depending on the frequency and the geometry of the trailing edge.

Keywords

Clay Vortex Convection Coherence Vorticity 

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Copyright information

© Springer-Verlag Berlin, Heidelberg 1989

Authors and Affiliations

  • William K. Blake
    • 1
  • Jonathan L. Gershfeld
    • 1
  1. 1.David Taylor Research CenterBethesdaUSA

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