Vorticity Dynamics in Bluff Body Stabilized Premixed Flames with External Pressure Gradients and Free-Stream Turbulence*

Previous studies based on direct numerical simulations of statistically planar premixed flames have shown that flame-generated turbulence is small compared to flow-generated turbulence for highly turbulent (i.e., high Karlovitz, low Damkohler) conditions. However, recent computational and experimental studies have indicated that the flame-generated component can be significant in configurations featuring large background pressure gradients. In this study, we use PeleC, a fully compressible reacting flow code featuring adaptive mesh refinement, to study vorticity dynamics in the near-wake region of a bluff-body stabilized premixed flame at near-blowoff conditions. We consider the combined effects of free-stream turbulence and mean background pressure gradients, as well as their cumulative effect, on the balance between flame-generated turbulence attributed to heat release from combustion and flow-generated turbulence inherent to the flow configuration. We describe how different terms in the vorticity magnitude transport equation vary with turbulence intensity and mean pressure gradient and connect these results with observed flame phenomena. Ultimately, this study will inform the development of improved models for large eddy simulations used to model real-world combustion systems.