Numerical investigation of the shock layer structure and heat transfer at the surface of a body in a supersonic dusty gas flow

The effect of high-speed two-phase gas-particle flow on a body or an obstacle is of considerable interest to mechanical engineers working in the fields of aeronautics, gas turbine design, industrial processing, etc. The presence of dispersed particles in the flow results in some new features of interaction between the flow and the streamlined surface. The first important feature is the direct Impact action of particles on the surface, and the second one is the influence of particles on the carrier gas flow. Behavior of particles in the flow near the surface can be very complex. Particles reflected from a body can collide with the incident ones that results in the formation of a rather thick near-wall layer in which particles move chaotically colliding with each other. On the one hand, the near-wall layer of particles in some ranges of governing parameters modifies significantly the carrier gas flow field in this area, and on the other it shields the surface from high-speed incident particles decreasing the intensity of the impact and heat action of particles. All these phenomena are extremely difficult for mathematical modeling and computational simulation, and very few papers are devoted to their analysis. In the present paper, the computational model of two-way coupled gas-particle flow with particle-particle collisions developed recently by the authors is applied to investigate the role of collisions between particles and the reverse effect of the dispersed phase on the carrier gas flow in the shock layer and, specifically, in the viscous boundary layer on the surface of a blunt body. Supersonic cross-wise flow of a dusty gas over a cylinder is analyzed. The main purpose of this study is to clarify how particle-particle collisions in the near-wall layer influence the flow structure and separately the heat transfer due to direct particle impacts and due to the modification of the carrier gas flow field caused by the dispersed phase. The carrier gas flow is governed by the complete Navier-Stokes equations modified by addition of the source terms describing the action of the dispersed phase. These equations are solved with the use of the finite-difference scheme. The flow of the collisional 'gas' of solid particles is simulated by the Monte Carlo method. The structure of the boundary layer on the body surface in the dusty gas was found to differ qualitatively depending on whether particle-particle collisions are taken into account or not. It was found that in the flow with coarse-grained particles, the heat flux to the surface due to particle impacts is much greater than the heat flux from the gas phase, whereas for fine particles these fluxes are of the same order. Numerical results show that the heat flux to the surface from the dusty gas flow is several times greater than the one from the pure gas flow. Refs. 1 (author)