Investigation of flow field structures induced by cavity geometry in supersonic Mach 2 conditions

Abstract

This study utilizes particle image velocimetry (PIV) to analyze the flow field dynamics in cavity flame holders with varying geometries, emphasizing the quantitative effects of shear layer impingement location and cavity geometry on recirculation zone behavior. Experimental findings reveal that reducing the aft ramp angle weakens high-speed reverse flow near the bottom of the cavity, promoting increased circulation values and a more stable flow structure through the suppression of small-scale vortices. Moreover, as the cavity length-to-depth ratio (L/D) increases, the shear layer impingement location shifts further toward the cavity bottom, causing the primary recirculation zone to diminish or vanish. Concurrently, the secondary recirculation zone expands, leading to a decrease in both average vorticity and circulation values. Enhanced positive axial flow is also observed within the cavity, attributed to the interaction between the shear layer and three-dimensional flow dynamics. This study offers new insights into the transient flow behavior within cavities under supersonic conditions, emphasizing the role of shear layer impingement and recirculation characteristics. The findings provide valuable guidance for the design of cavity-based flameholders, bridging the gap between fundamental flow understanding and practical scramjet combustor applications.