Influence of gas molecular weight on jet penetration and mixing in supersonic transverse air flow in channel

Abstract

In the paper, numerical analysis is performed of 3D supersonic turbulent flows in a channel with a sudden expansion (backward-facing step) and jets injected transversally from the channel walls before the channel sudden expansion. The numerical simulations were performed under the conditions of experiments maid at the hot-shot wind tunnel IT-302M ITAM SB RAS. In the experiments, Mach number at the entrance of the channel was M = 4, the total temperature was T0 = 1500÷2400 K, and the total pressure was P0 = 1÷10 MPa. As secondary injecting gas, argon and hydrogen were used. The injectors were located before the backward facing step on the top and bottom walls of the model. Two-jet and eight-jet injection schemes were investigated experimentally and numerically. Mathematical modeling was carried out using ANSYS Fluent on the basis of the Reynolds-Averaged Navier-Stokes equations supplemented by the k-ω SST turbulence model. A comparison of the calculated and experimental data indicates that they are in satisfactory agreement. The calculated results made it possible to obtain a clearer understanding of the flow structure in the channel and reveal influence of the injection scheme and gas molecular weight on the mixing processes, pressure and temperature fields and the distribution of the mixture concentration over the length.