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Propagation of weak shocks through a random medium

Hesselink, Lambertus and Sturtevant, Bradford (1988) Propagation of weak shocks through a random medium. Journal of Fluid Mechanics, 196 . pp. 513-553. ISSN 0022-1120. http://resolver.caltech.edu/CaltechAUTHORS:20120604-095844884

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Abstract

The propagation of weak shock waves (M_s = 1.007, 1.03 and 1.1) through a statistically uniform random medium has been investigated experimentally in a shock tube. The wave-from geometry, rise time and amplitude of initially plane shocks which have propagated through a random mixture of helium and refrigerant 12 are measured. The effect of shock propagation on the properties of the random medium is visualized with schlieren and shadow photography. The pressure histories of the distorted shock waves reflecting from a normal end wall are observed to be both peaked and rounded. In the rounded case the perturbed shock is found to be made up of a succession of weak, slightly curved fronts with a total effective rise time orders of magnitude greater than the classical Taylor thickness. The radius of curvature of the weakest shocks after propagating through the random medium is inferred from observations at two downstream stations to be about 7 times the integral scale of the gas inhomogeneities. It is concluded that the observed distortions of the wave fronts can best be explained in terms of random focusing and defocusing of the front by the inhomogeneities in the medium. A ray-tracing calculation has been used to interpret the experimental observations. It is found that geometrical considerations are sufficient to account for many of the effects observed on the shocks.


Item Type:Article
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http://dx.doi.org/10.1017/S0022112088002800 DOIUNSPECIFIED
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=394783PublisherUNSPECIFIED
Additional Information:© 1988 Cambridge University Press. Received 15 April 1985 and in revised form 6 April 1988. Published online: 21 April 2006. This work was supported under NSF Grant number MEA-8120092. L.H. acknowledges the support of the Dutch Government, a Fullbright Grant and a Josephine de Karman Fellowship. We are indebted to Professor H. W. Liepmann for stimulating support and Professor D. Coles who has made significant contributions to this work, in particular during the design stage of the experimental apparatus. The authors are also indebted to Dr B. White and Mr D. Madura and the Medical Image Analysis Facility, Jet Propulsion Laboratory, for their aid in processing data from photographs.
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NSFMEA-8120092
Dutch GovernmentUNSPECIFIED
Fullbright Grant UNSPECIFIED
Josephine de Karman FellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20120604-095844884
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120604-095844884
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ID Code:31793
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:05 Jun 2012 16:43
Last Modified:26 Dec 2012 15:18

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