Experimental investigation of combustion stabilization modes in a cavity-based supersonic combustor with different wall divergence angles

Abstract

Optical diagnostics and pressure measurements are carried out to investigate the characteristics of cavity-assisted hydrogen jet combustion in a Mach 2.52 supersonic flow which simulates flight Mach 5.5 ∼ 6 conditions. Two combustor configurations with wall divergence angles being 2.25° and 3.5°, and two injection schemes are designed. Main attention is focused on the influences of the combustor wall divergence angles and injection schemes on combustion stabilization modes. The experimental results show that two totally different combustion stabilization modes and transition processes between combustion stabilization modes are detected. Heat release and jet–cavity interactions are supposed to play an important role in the transition of combustion stabilization modes. In addition to injection schemes and the cavity configuration, the combustor wall divergence angle is demonstrated to obviously affect the combustion stabilization modes in the supersonic cavity flows, suggesting that the divergence angle should be seriously considered in the supersonic combustion organization. The contrastive experiments also show that as long as combined cavity shear layer/recirculation combustion stabilization mode is achieved, the divergence angle should be smaller and the injection distance should be shorter with all the possible means to obtain more stable combustion in present condition. Meanwhile, it needs to be more cautious to design injection schemes if the combustor wall divergence angle is larger.

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