Shock wave reflection from a wedge in a dusty gas

The present paper contains a detailed study of shock wave reflection from a wedge placed in various suspensions. In past works, the incident shock propagated initially in pure gas and the suspension started only at the leading edge of the deflecting wedge. However, in the present case the entire flow field is filled with a gas-dust suspension and the initial shock wave has steady-state structure relative to the shock front. In former studies the transmitted shock wave starts its propagation into the suspension and is reflected from the wedge at the same time. It is therefore obvious that the two unrelated processes of (2D) reflection and (1D) "transitional" relaxation occur simultaneously. In the present case the suspension behind the incident shock wave has reached steady state (i.e., it is a traveling wave) before the shock reaches the wedge leading edge. The reflection process from the deflecting wedge is studied for different dust mass loadings and different dust-particle diameter. It is shown that when the dust loading is low and the dust particle diameter is small the wave reflection pattern is similar to that observed in a similar pure gas case. In addition, an equilibrium state is reached, behind the evolved waves, very quickly. On the other hand, when the dust loading is relatively high and/or the dust particle diameter is relatively large, the observed reflection wave pattern is very different from that seen in a similar pure gas case. In such cases it takes much longer time to reach an equilibrium state behind the reflecting waves. It is also shown that the dust presence significantly affects the (gas) pressure on the wedge surface. The higher the dust loading is, the higher the pressure on the wedge surface. Suspensions composed of solid particle of different size, but having the same dust mass loading, will approach the same equilibrium pressure. However, it will take longer time to reach an equilibrium state for suspensions having large diameter particles. (C) 2004 Elsevier Ltd. All rights reserved