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A cylindrical sound pulse in a rotating gas

Published online by Cambridge University Press:  28 March 2006

L. E. Fraenkel
Affiliation:
Aeronautics Department, Imperial College, London
This work was done while the author was at the Guggenheim Aeronautical Laboratory, California Institute of Technology.

Abstract

This paper deals with the propagation of a sound pulse into a gas which initially has solid-body rotation and constant temperature, the initial pressure and density increasing outwards like ex, where x is the square of a certain dimensionless radial co-ordinate. The perturbations are due to a source-like disturbance on the axis of symmetry, which begins to act at time t = 0: most attention is paid to source strengths which vary in time like a Dirac pulse or a step function, but the following remarks apply generally.

Immediately behind the wave front the perturbation velocity and temperature decay like ex, while the (absolute) perturbation pressure and density grow like e½x (the relative pressure and density increments, which are referred to local conditions in the undisturbed state, then also decay like ex). The rotation also introduces oscillations in flows which, with the same disturbance at the origin and no rotation, would vary monotonically with time at a given point.

Type
Research Article
Copyright
© 1959 Cambridge University Press

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References

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