Numerical simulation research on ignition and flame propagation in strut/cavity combustor

Inlet distortion significantly influences the overall performance of afterburners. This study numerically investigates the effects of non-uniform inlet velocity and temperature profiles on the flow characteristics, ignition limits, and flame propagation behavior in a strut/cavity-based combustor under sub-atmospheric pressure conditions, with an inlet velocity of 109.9 m/s and an inlet temperature of 1043 K. The results reveal that, compared to a uniform velocity inflow, increasing the velocity non-uniformity raises the ignition fuel-air ratio. However, when temperature distortion is coupled with velocity distortion, the ignition boundary fuel-air ratio decreases. The location of the velocity distortion peak markedly affects the recirculation vortex structure. The ignition equivalence ratio reaches its minimum when the distortion peak is positioned at the upper region, followed by the lower peak, while the middle peak yields the highest value. Despite varying distortion conditions, the flame propagation paths remain qualitatively similar: the flame within the cavity is entrained toward the strut trailing edge by the recirculation zone and subsequently propagates downstream. Among the cases examined, flame propagation is fastest when the distortion peak is located at the middle position, and the addition of temperature distortion further accelerates flame propagation. Nevertheless, an excessively high temperature distortion index may introduce the risk of auto-ignition. Overall, this investigation into flow, mixing, and combustion under non-uniform inlet conditions provides valuable insights for the design and application of strut/cavity-based combustors operating under complex inflow conditions.