Influence of backward-facing step on the mixing efficiency of multi microjets at supersonic flow

The injection of the fuel is a highly important process for the enhancement of the scramjets. In this article, the presence of the backward-facing step on the mixing of the mull-fuel jets is expansively studied. The primary attention of this article is to scrutinize the flow feature of the fuel jet under the backward-facing step. The mixing mechanism of the fuel is also studied to compare this injection system with conventional methods. To do this, a 3-dimensional model is chosen to consider the real physic of the problem. Reynolds Average Navier-Stocks equations are solved with a computational fluid dynamic method to visualize the flow pattern of the fuel jet at the free stream Mach number of 4. SST turbulence model is also used for the calculation of the viscosity. Our results indicate that increasing the jet space from 4 to 10 times of jet diameter in the presence of the backward-facing step increases the mixing efficiency up to 20% in the downstream. Our findings depict that augmenting the number of fuel injectors from 4 to 8 augments the mixing rate up to 15% inside the combustor.