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Measurements of unsteady pressures and wake fluctuations for flow over a cylinder at supercritical Reynolds number

Spitzer, Robert Edward (1965) Measurements of unsteady pressures and wake fluctuations for flow over a cylinder at supercritical Reynolds number. Engineer's thesis, California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-01222004-093919

Abstract

A test was conducted to measure and map the unsteady pressure fluctuations over the surface of a smooth, cantilevered, circular cylinder in the supercritical Reynolds number range from 2.5 x 10[superscript 5] to 7.5 x 10[superscript 5]. Lift fluctuations were measured, hot-wire wake surveys were made, and the effects of boundary-layer tripping were investigated. Power spectral densities were computed from recordings of the fluctuations, and cross-correlation coefficients were determined.

Pressure fluctuations were found to be small in magnitude but with relatively high axial correlation except at the points of flow separation. Definite evidence of periodicity was found in the pressure fluctuations excluding those in the region of flow separation. Fluctuating lift was found to be random in nature in the supercritical regime. Power spectra of wake velocity fluctuations after transition showed largely turbulent patterns with perhaps some dominance at Strouhal number near 0.4 seen on occasion. Localized boundary-layer tripping caused earlier flow separation, significant increases in pressure and lift fluctuations, a greater degree of axial correlation, and a shift in the power spectra to indicate periodic effects.

Item Type:Thesis (Engineer's thesis)
Degree Grantor:California Institute of Technology
Major Option:Aeronautics
Thesis Committee:
  • Fung, Y. C. (chair)
Defense Date:31 December 1964
Record Number:etd-01222004-093919
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-01222004-093919
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:265
Collection:CaltechTHESES
Deposited By: Imported from ETD-db
Deposited On:28 Jan 2004
Last Modified:25 Dec 2012 14:58

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