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Department of Aerospace and Mechanical Engineering
University of Arizona
Abstract-
Rayleigh-Taylor and Richtmyer-Meshkov instabilities are two very
fundamental fluid phenomena that are of importance to the fields of
astrophysics, inertial fusion and supersonic combustion.
Rayleigh-Taylor instability occurs whenever a heavy fluid lies over a
lighter one in a constant gravitational field and Richtmyer-Meshkov
instability is the related phenomena that is generated when the
acceleration is impulsive in nature, such as that generated by a
shock wave that passes over an interface separating two differing
density gases. Three novel experiments will be presented which
improve upon previous studies in that very well defined initial
states are obtained. The first is a shock tube experiment in which a
well controlled interface is generated by flowing a light and a heavy
gas from opposite ends of a vertical shock tube. The second is an
incompressible experiment in which an impulsive acceleration is given
to a box containing two miscible liquids by bouncing it off of a
fixed spring. In the third experiment Rayleigh-Taylor instability is
generated by accelerating a two-liquid system downward using a weight
and pulley apparatus. In all three experiments, a sinusoidal initial
shape is given to the interfaces by gently oscillating the fluids in
the horizontal direction to produce standing waves, and PLIF is used
to visualize the flow. These experiments provide particularly well
visualized images of the instabilities far into the nonlinear regime
and yield initial growth rate measurements that are in very good
agreement with linear stability theories.
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