Richtmyer–Meshkov instability induced by two successive shock waves is experimentally studied in a specific shock tube. To create two successive shock waves synchronously, a driver section is added between the driver and driven sections of the standard shock tube, and an electronically controlled membrane rupture equipment is adopted. The shock-tube flow after the membranes rupture is well described by combining the shock relations, isentropic wave relations with compatibility relations across the contact surface (region). The new shock tube is capable of generating two successive shock waves with controllable strengths and time interval, and provides a relatively ‘clean’ wave system. Then the developments of single-mode light–heavy interfaces with different initial conditions induced by two successive shock waves are investigated. The initial amplitudes are all small enough such that the first-shocked interface is within the linear growth regime at the arrival of the second shock. The results show that if the pre-second-shock perturbation amplitude is small, the linear, nonlinear and modal evolutions of the double-shocked interface can be reasonably predicted by the existing models proposed for predicting the perturbation growth induced by a single shock. For the double-shocked interface, the second shock provides an additional perturbation velocity field to the original one introduced by the first shock impact. The validity of the linear superposition model indicates that the linear superposition of these two perturbation velocity fields is satisfied. Therefore, a double-shocked interface evolves similarly to a single-shocked interface provided that their postshock amplitudes and linear growth rates are the same.

Attenuation and even freeze-out (amplitude growth stagnation) of the perturbation amplitude growth of a shocked SF $_6$ –air interface are first realized in shock-tube experiments through reflected rarefaction waves, which produce reverse baroclinic vorticity offsetting the vorticity deposited by the shock. A theoretical model is constructed to predict the perturbation growth after the impact of rarefaction waves, and seven possibilities of amplitude growth are analysed. Experimentally, a planar air–helium interface is used to produce reflected rarefaction waves. Through changing the perturbation wavelength and the time interval of two impacts, five experiments with specific initial conditions are carried out, and three different possibilities of perturbation growth attenuation are realized.

The high-amplitude effect on the Richtmyer-Meshkov instability flow characteristics is investigated by examining the interaction of a planar shock with a single-mode air-SF6 interface both experimentally and numerically. In experiments, the soap-film technique is adopted to generate well-defined initial interfaces, and the shocked flows are recorded by high-speed schlieren photography. Numerical simulations are performed to highlight effects of wave patterns on interface movements at the early stage. For cases with high initial amplitudes, a cavity is formed at each spike tip. The cavity formation is ascribed to the vorticity deposition on the slip lines resulting from the Mach reflection of transmitted shock wave. A series of transverse shocks introduce the secondary compression effect, which changes the interface morphology and causes the failure of the impulsive model in predicting the amplitude linear growth rate. Those modified linear models considering a reduction factor are also found incapable of accurately predicting the linear growth rate. Moreover, a non-monotone dependence of linear growth rate on initial amplitude is observed. Although similar observations were reported in previous numerical simulations, they have never been reported in experiments before. According to the pressure and velocity distributions, the effects of shock-shock interaction on the movements of the interface peak and trough are demonstrated, and the mechanism of non-monotone dependence is discussed. The validity of the existing nonlinear model proposed for predicting the development of a single-mode interface is further tested. It is shown that the applicability of the model worsens as the initial amplitude or dimensionless time increases.