The Influence of Turbulence-Chemistry Interaction Modelling for Supersonic Combustion

Past studies of supersonic reacting hydrogen jets have shown that simple laminar chemistry provides comparable results to more complex turbulence-chemistry interaction modelling. This has led to the neglection of combustion modelling for many simulations of supersonic combustion conducted today. This paper aims to investigate the influence of turbulence-chemistry interaction modelling through the simulation of a more realistic combustor geometry, the SCHOLAR scramjet test case. Results from laminar chemistry and the assumed PDF combustion model are compared using two detailed chemical mechanisms. It is shown that the inclusion of combustion modelling has a minimal impact on the results obtained, possibly due to alteration of the turbulence energy spectrum from that expected under subsonic conditions. It is suggested that this leads to the smallest turbulent structures in the flow being larger than the flame thickness and therefore unable to enter the reaction zone. This is supported by analysis of the supersonic combustion regime, showing an expected flamelet-like behaviour.