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Sound radiation from surface cutouts in high speed flow

Citation

Karamcheti, Krishnamurty (1956) Sound radiation from surface cutouts in high speed flow. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-03262004-114458

Abstract

In an experimental investigation of subsonic and supersonic flows of air past rectangular cavities cut into a flat surface it was discovered that the cavities emit a strong acoustic radiation.

The frequency of the sound-producing oscillations measured by a hot wire in the cavity was found to be inversely proportional to the breadth for fixed depth. For fixed breadth the frequency was found to increase, though not systematically, with a decrease in depth.

A non-dimensional frequency S is defined in terms of the frequency of emission, the gap breadth, and the free stream velocity. The dependence of S on the various parameters in the problem, such as Mach number, Reynolds number and ratio of the boundary layer thickness to a dimension of the cavity, is discussed in light of appropriate experiments.

An estimate of the intensity of the radiation was obtained by means of an optical interferometer of the Mach-Zehnder type. For points located at 3 to 4 cavity breadths from the cavity, intensities of the order of 100 - 150 decibels were found for sound fields from cavities 0.1" deep and 0.1 to 0.2 inch broad at Mach numbers 0.7 to 0.85.

Possible mechanisms for the sound production by the cavities are discussed.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Roshko, Anatol
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1956
Record Number:CaltechETD:etd-03262004-114458
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-03262004-114458
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1129
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:26 Mar 2004
Last Modified:26 Dec 2012 02:35

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