Dusty gas flow in a nozzle

The flow in a converging-diverging nozzle is studied numerically. The study covers two different flow cases. First, the flow of a pure gas is studied and thereafter, a flow of a suspension composed of gas seeded with small, spherical, solid particles is considered under the same initial and boundary conditions used in solving the pure gas case. In both cases the solution covers the entire flow history, from its initiation and until a steady state flow is reached. The covered flow domain includes both the flow field inside the nozzle and part of the free jet flow outside of the nozzle exit plane. The solution for the suspension case is repeated for different solid particle diameters, ranging from 0.5 μm to 50 μm, and different dust loading ratios. It is shown that the presence of solid particles in the flow has a significant effect on the developed flow field, inside and outside the nozzle. In particular, by a proper choice of the solid particles diameter lateral pressure waves and the secondary shock wave can be significantly attenuated. The solid particles size has also a marked effect on the position and size of the Mach disk appearing in the free jet flow. It is also shown that in a suspension case a steady state flow is reached faster than in a similar pure gas flow.