Abstract
The Richtmyer–Meshkov instability on a three-dimensional single-mode light/heavy interface is experimentally studied in a converging shock tube. The converging shock tube has a slender test section so that the non-uniform feature of the shocked flow is amply exhibited in a long testing time. A deceleration phenomenon is evident in the unperturbed interface subjected to a converging shock. The single-mode interface presents three-dimensional characteristics because of its minimum surface feature, which leads to the stratified evolution of the shocked interface. For the symmetry interface, it is quantitatively found that the perturbation amplitude experiences a rapid growth to a maximum value after shock compression and finally drops quickly before the reshock. This quick reduction of the interface amplitude is ascribed to a significant Rayleigh–Taylor stabilization effect caused by the deceleration of the light/heavy interface. The long-term effect of the Rayleigh–Taylor stabilization even leads to a phase inversion on the interface before the reshock when the initial interface has sufficiently small perturbations. It is also found that the amplitude growth is strongly suppressed by the three-dimensional effect, which facilitates the occurrence of the phase inversion.
Highlights
The Richtmyer–Meshkov (RM) instability (Richtmyer 1960; Meshkov 1969) occurs when an arbitrarily perturbed interface separating two different fluids is impulsively accelerated by a shock wave
The development of perturbation amplitude is nearly linear at early stages and is much slower than the prediction of the 2-D impulsive model, but coincides well with the prediction of the 3-D linear model which considers the effects of the opposite principal curvatures of the initial interface
A RTPI is found at the symmetry interface with a small initial amplitude, which is the result of the strong and long-term effect of the RT stabilization
Summary
The Richtmyer–Meshkov (RM) instability (Richtmyer 1960; Meshkov 1969) occurs when an arbitrarily perturbed interface separating two different fluids is impulsively accelerated by a shock wave. Hornung & Sturtevant (2003) studied the growth of a multi-mode initial interface, formed by sandwiching a polymeric membrane between wire-mesh frames, in a conical geometry, and found that the turbulent mixing zone at very late time has a relatively larger growth rate than the planar counterpart. These studies focused on the turbulent mixing stage, and a direct experimental observation of the very complex process of the converging RM instability is still desirable. More experiments on the single-mode interface are needed to explore physical mechanisms in the converging RM instability in a relatively long time scale
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