Review of cavity ignition in supersonic flows

The cavity-based flameholder is a promising device in supersonic combustion issues in a scramjet engine and it also provides a favorable ignition environment inside the cavity owing to low speed recirculation flows and relatively high static temperature. The cavity ignition process as the beginning phase of the flameholding process is of vital importance to the performance of the scramjet engine and also operation safety of the aircraft. This paper reports recent research progress on the complex cavity ignition process in supersonic flows, which is summarized from five aspects, namely study on non-reacting flows regarding ignition, effect of ignition method, effect of igniter setups, effect of cavity fueling and effect of cavity geometry. Aspects of the non-reacting and reacting cavity flow fields prior to and during ignition process are discussed comprehensively with emphasis on the effects of above ignition influencing factors. In addition, typical ignition methods are introduced in detail and compared to describe the cavity ignition operability in real scramjet applications. Finally, some promising recommendations have also been proposed for the cavity ignition process. •Recent research progress on cavity ignition process in supersonic flows was reviewed.•Typical cavity ignition techniques were introduced in detail.•Promising suggestions for cavity ignition process were also proposed.