Study of a supersonic reacting wall jet with a variable turbulent Prandtl and Schmidt number approach

Abstract Within the context of supersonic combustion modeling in air-breathing propulsion, the turbulent Prandtl and turbulent Schmidt numbers have a profound effect on the resulting predictions. This work considers a Scalar Fluctuation Model (SFM) introducing two extra transport equations in order to specify variable values for turbulent Prandtl and turbulent Schmidt numbers within a Reynolds-Averaged Navier-Stokes (RANS) framework relying on a gradient diffusion hypothesis for both the turbulent heat and mass flux. The SFM is applied in conjunction with a two-equation linear eddy viscosity model. In order to study the effect of the different modeling choices, the supersonic reacting wall jet experiment of Burrows and Kurkov (1973, AIAA Journal) is considered. A strong effect of Turbulence Chemistry Interaction (TCI) through an assumed PDF approach on the SFM is observed and needs to be enabled in order for predictions to be within experimental observation bounds in terms of ignition delay. Overall, the presented SFM methodology could be a viable candidate for supersonic combustion studies.