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 [24] 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.

在空气推进推进中的超音速燃烧模型中，湍流的Prandtl和湍流的Schmidt数对所得的预测产生深远的影响。这项工作考虑引入两个额外的输运方程的标量涨落模型（SFM），以便在依赖于两个湍流的梯度扩散假设的雷诺平均Navier-Stokes（RANS）框架中指定湍流Prandtl和湍流Schmidt数的变量值热和质量通量。SFM与两方程式线性涡流粘度模型结合使用。为了研究不同建模选择的影响，考虑了Burrows和Kurkov [24]的超声反应壁射流实验。观察到通过假定的PDF方法对SFM产生的湍流化学相互作用（TCI）的强烈影响，并且需要启用以使预测在点火延迟方面处于实验观察范围之内。总体而言，提出的SFM方法可能是超音速燃烧研究的可行候选者。