  Supersonic combustion plays a vital role in various applications, including
scramjets, dual-mode ramjets, and pulse detonation engines. However, the flame
characteristics can vary significantly, depending on the application. To model
supersonic combustion, large eddy simulation coupled with a partially stirred
reactor (PaSR) is commonly used. This method assumes that reactions occur at
turbulent fine flame structure in a computational cell, making it less
effective for flames governed by not only turbulent mixing but also homogenous
autoignition, which is common under supersonic flow. To address this
limitation, this study proposes a novel dynamic combustion model to enable more
versatile modeling of supersonic flames. The model utilizes a two-delta
probability density function, which represents the sub-grid composition
variation and models the filtered sub-grid reaction rate. The corresponding
weights are dynamically modeled based on the level of cell composition
inhomogeneity. The new dynamic model is tested in a supersonic combustion case
study with a strut-cavity flame holder. Results demonstrate that the new
dynamic model can properly recover the limits of supersonic flames that are
primarily governed by homogenous autoignition and turbulent mixing.
