438 / 2019-03-05 19:53:09

Numerical study of shock-dusty gas cylinder interaction

dusty-gas cylinder,non-equilibrium effect,shock wave,instability

全体主题 > Interface Instabilities at Extremes

The shock-cylinder interaction is a typical physical problem in compressible high-speed flow. Previous studies mainly focused on the flow structure in an ideal gas environment. However, in real applications such as explosion safety, dusty plasma in the galaxy and solid-fuel booster, the environmental gas is usually seeded with large amounts of small solid particles. In the dusty gas, the non-equilibrium effect caused by particle relaxation seriously affects the characteristic structure of the flow field.
A compressible multi-component solver with an adaptive mesh refinement technique is used to simulate the interaction of a planar shock wave with a dusty-gas cylinder in this talk. The influence of non-equilibrium effect caused by the particle relaxation, which is closely related to the particle radius and shock strength, on the evolution of particle cylinder is emphasized. The particle cloud behaves like an equilibrium gas cylinder with effective physical properties for a small particle radius. Specifically, the transmitted shock converges continually within the cylinder and then focuses at a region near the downstream interface, producing a local high pressure zone. Also, there exist notable secondary instabilities along the cylinder edge as well as evident particle roll-up, causing a relatively large width and height of the shocked cylinder at the early stage. The flow features approach those of a frozen flow of pure air with the increase of particle radius. Especially, the transmitted shock propagates more quickly with a weaker strength and a smaller curvature, resulting in a weaken shock focusing. Also, particles would escape from the vortex core formed at late stages due to the large inertia, which induces a greater degree of particle dispersion. A large particle radius as well as a strong incident shock can greatly facilitate the particle escape is covered in this study. Last, the high dependence of particle escape on particle radius and shock strength is discussed in this talk, which is reasonably explained by the theory of Luo and the SZ circulation model. These present results are useful for assessing the effect of tracing particles on the actual gas flow using advanced flow diagnostic techniques such as PIV.