Dynamics of shock waves in the particle-laden gas medium

Abstract

The flow behind shock waves in the particle-laden gas medium shows complex relaxation pheonomenon due to momentum and energy exchanges between the two phases. In this dessertation, numerical analyses of the gas-particle mixed flows were preformed using a two-fluid model. TVD and MacCormack schmes were employed to solve the gas particle equations, respectively. Investigated in depth are variation of the flow structures depending on the particle composition in the gas medium and the shock wave interaction effect for unsteady and steady problems. To validate the numerical process, the gas-only phase flow was fiist solved for the moving shock waves reflected from a compression corner. The numerical result agreed very well the experimental data, and it was found that supersonic flow existed locally in the triangular region between the Mach stem and the slipline. In the case of two phase flows, interaction effect was more distinguished for the smaller particles and for the higher mass fraction ratios;supersonic flow was observed extended locally to the second triple point. The shock structures in the particle-laden gas flow became quite complicated, resembling the Double Mach Reflection. Teh flow domain was divided by shock waves and contact discontinuity line into three characteristic zones:the zone of inert uniform particles, the particulate relaxation zone, and the partcle-free zone.the speed of the moving shock wave was retarded and the peak density in the relaxation zone was increased as the gas-particle interaction became higher. The computational results of the steady highly-underexpanded free jets also showed increased interaction effect with the smaller particles and with the higher loading ratios. The reduced gas momentum caused by the particle interaction was blamed for the weakened Mach disk that moved downstreams. Behind the Mach disk, the gas was reaccelerated to the supersonic speed due to the higher particle velocities;this is in cntrast to the pure g...