Thermal Effects of Particles on Hypersonic Ablation

摘要

We have presented a model for the study of thermal effects of solid particles carried by the gas stream on thermal ablation in hypersonic flow. A basic assumption and, hence, a limitation of this simplified model is that of sparse particles, and it is made so that the interactions between particles and the effects of particles on the gas stream and on the basic particle-free ablation model can be neglected in the first order of the approximation. The solutions are presented in simple, analytical form so that their parametric dependence is apparent. To be sure, they are approximate solutions of the governing equations obtained by an integral method. The accuracy of the solutions can, of course, be improved by solving the equations exactly, but the present solutions seem adequate in providing a qualitative understanding of the physics provided by the simplified model. It seems feasible to make some reasonable modifications to the present model to make it more realistic. For example, a more accurate model for calculating the convection heat transfer between the particle and the surrounding melt can be developed and used to account for the variation of the heat transfer rates around the particle surface. Also, phase changes of the particle during the course of its travel in the melt layer can be allowed by appropriate changes of the boundary conditions of the heat conduction equations. It would be interesting, and also important, to consider the dynamic effects of particles on ablation (for example, see Cheung et al.), using the simple results presented in the present paper as a starting point.