Numerical study on the effect of equivalence ratio in passive strut configuration

Mixing and combustion of air and fuel take place at high velocities in a scramjet. This leads to an extended area of research to analyze the mixing and combustion of air and fuel. The present study intends to address the impact of equivalence ratio on the mixing performance of the two passive that induces backpressure. Hybrid RANS/LES simulation is conducted using an improved delayed detached eddy simulation (IDDES) turbulence model. The different cases of equivalence ratio are compared. The data-driven modal analysis is conducted using POD and DMD to understand the different modes responsible for the enhancement of mixing. The equivalence ratio was found to have a significant impact on the mixing characteristics of the scramjet combustor. As the equivalence ratio increased, mixing efficiency decreased. The phase portrait of the POD deviates from a circle as the equivalence ratio increases. The frequency of the temporal dominating coherent structure was observed to be increasing with the increase in equivalence ratio. The change in equivalence ratio also affected the acoustics characteristics of the flow.