Numerical Investigations Of The Interaction Mechanisms Of Shock Waves With Different In-Terfaces And The Induced Wave Structures

Shock waves can be induced during the process of armament launch and explosions, which are harmful to human bodies and equipment around the sites. Hence, it is of im-portant engineering application background to investigate the interaction mechanism of shock wave with interfaces of different materials and their induced wave structures. In ad-dition, there are many intricate fluid physical phenomena unrevealed on these problems, such as the vortex induced by shock wave, interaction of shock wave with vortex etc.. Therefore, the studies on interactions of shock waves with interfaces of different-materials are also of important academic significance. In this paper, Euler equations and large-eddy simulations combined with high order numerical scheme, immersed boundary method and adaptive mesh refinement technic were used, respectively, to simulate phenomena of shock waves interacting with both gas and solid interfaces. The main work and achievements are described mainly as follows:Two typical interactions of shock wave with solid boundaries, such as shock waves pass a triangular wedge (called Schardin’s Problem), and shock wave past around a rectan-gle cavity were carried out to investigate the interacting process of shock wave with rigid interfaces. The flow phenomena in Schardin’s problem such as, the formation of Mach re-flection, shock wave diffraction, the induction of the main vortex, shock-vortex interaction, shock-vortexlets interaction and generation of acoustic waves, were expatiated in detail. The inducing process of vortexlets along the shear layer of main vortex as well as the mechanism of generating acoustic waves during the the last stage of interaction process of the shock wave and vortexlets have been presented. For the interaction of shock wave with rectangular cavity, shock wave diffraction and the induced main vortex were discussed in detail. Moreover, the processes of diffracted wave reflecting inside the cavity and its inter-acting with main vortex were emphasized.Attenuation of shock wave during its interaction with rigid obstacles of various shapes mounted at the bottom of a shock tube was also investigated numerically. Efforts have been made to understand the mechanism of shock wave attenuation during its interaction pro-cess by analyzing the variation of shock wave structures as well as the pressure variation of wave front. It is found that the main reason for shock wave attenuating is caused by its merging with the expansive waves induced by its diffraction. The influences of obstacle shape on shock wave attenuation were examined from three aspects:width of the top side of obstacles, the slope of its windward and leeward side. It is found that the triangular ob-stacle with minus slope of windward side has the best effects on shock wave attenuation compared with other shapes. The optimal shape of obstacle for shock wave attenuation was educed, and its effect on shock wave attenuation was validated by comparing with usual obstacles under the same initial conditions.Lastly, the interaction processes of a planar shock wave with R22circular cylinders, SF6isosceles trapezium cylinders and SF6bubbles were numerically simulated. The nu-merical results clearly showed the deformation of cylinder induced by the Richtmy-er-Meshkov instability. In addition, the generation mechanisms of jets induced by the fo-cusing of refracted shock near the right interface of the inner cylinder were revealed, as well as the roll-up of the secondary vortexes along the interfaces. The mixing mechanism of R22gas with air was also expatiated. Furthermore, the evolution of R22cylinder under reshock conditions was numerically simulated with two different end wall distances. The generating process of double jets induced by reflected waves as well as the complex wave structures inside the heavy gas cylinder and their development were also analyzed in detail. The interaction processes of a planar shock wave with two isosceles trapezia of SF6cylin-ders were also numerically simulated. The wave structures, vorticity and the shape of the interfaces were revealed. Finally, the three-dimensional deformations and instability of SF6spherical bubble induced by planar incident shock wave were studied numerically. The numerical results reveal the generation process of jet induced by refracted shock wave fo-cusing inside SF6bubble, the development of the jet structure and the generation mecha-nism of secondary vortex ring were also discussed.