Recent research progress on unstart mechanism, detection and control of hypersonic inlet

The present paper aims to provide a summary report on recent research progress about unstart mechanism, detection and control of hypersonic inlet to help the researchers working on hypersonic inlet to further their work. It covers unstart patterns with their mechanisms, monitoring methods for start/unstart classification and detection, characterization methods for unstart margin, and methods for unstart suppression and control. At first, the inner mechanisms of various unstart patterns have been surveyed and classified, which are respectively caused by contraction ratio (CR)/internal contraction ratio (ICR), backpressure, Mach number and heat release. Followed, monitoring methods (one is for start/unstart classification and the other is for unstart detection) have been introduced respectively. Thirdly, three types of techniques for margin characterization of unstart are listed, which are respectively based on backpressure, the location of shock train leading edge and pressure distribution. At last, unstart suppression and control have been discussed, which are based on flow control or feedback control.