Experimental Study On The Interaction Of Single-mode Interface With Cylindrical Converging Shock

When a shock wave interacts with an initially perturbed interface which separates two different fluids, the vorticity occurs due to the misalignment of the pressure and the density gradients. The accumulated vorticity leads to the increase of the perturbation amplitude and the instability on the interface with complicated fluid phenomena, and the turbulent mixing finally appears. This flow instability phenomenon is often referred to as the Richtmyer-Meshkov (RM) instability. In recent years, studies on the RM instability have received much attention due to the extensive applications in scientific and industrial fields. In particular, the RM instability with respect to the converging shock, has become more and more attractive due to its significant application in high-energy physics field. However, in laboratory conditions, it is always a big challenge to generate perfect converging shock waves in the RM instability experiments. In this thesis, we design and manufacture a semi-annular converging shock tube to generate cylindrical converging shock waves, and study the RM instability induced by the converging shock using both experimental and numerical methods.In comparison with previous converging shock tubes, the design of the semi-annular shock tube follows the mechanism of the annular structure, but the annular channel and the test section are cut into half and assembled in a self-constructed manner, which brings great convenience for the interface formation and the flow visualization. The high-speed schlieren photography is used to capture the complete evolution of single-mode interface interacted by the cylindrical converging shock wave. By changing the incident shock strengths and the shapes of the initial interface, we obtain the variations with time of the interface deformation and the perturbation amplitude. We further study the effects of the incident shock Mach number and the initial perturbation amplitude on the complete process of the interface evolution. The results indicate that the RM instability induced by converging shock waves is different from that in the planar shock case, which can be attributed to the convergence effects, including the geometric convergence, the flow compressibility and the phase inversion.