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The effect of a density difference on shear-layer instability

Published online by Cambridge University Press:  29 March 2006

Robert F. Davey  and
Anatol Roshko
Robert F. Davey
Affiliation:
California Institute of Technology, Pasadena
Anatol Roshko
Affiliation:
California Institute of Technology, Pasadena
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Abstract

Measurements of mass flow rate and mean density have been made in separated laminar boundary layers with large transverse density gradients. Two-dimensional shear layers were formed by exhausting a half-jet of one gas into a reservoir of another gas with a different molecular weight. Two freons with a density ratio of 1-98 and unusual properties which permitted the measurement of the mass flow rate with a single hot wire were used. A n analysis of the mass flow rate fluctuations showed that a negative density gradient (i.e. light gas flowing into heavy) increases the amplification rate of the instability oscillations and reduces the frequency and wave number. Opposite trends were observed when the density gradient was positive. These findings are in agreement with recent theoretical predictions.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 53 , Issue 3 , 13 June 1972 , pp. 523 - 543
Copyright
© 1972 Cambridge University Press

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