Progress in the basic application issues of the pulse detonation rocket engine

The pulse detonation rocket engine is a propulsion system which obtains thrust by repeatedly generating detonation waves. It has the potential advantages of high thermal efficiency, simple structure and wide applications. In order to realize the potential advantages, various theoretical and engineering problems need to be solved before it goes into practical application. Numerous efforts have been made to establish a systematic set of theories and guidelines that could be universally applied to detonation-based propulsion designs, thereby laying solid theoretical and technical foundations for the birth of novel aerospace propulsion engines. The progress in some basic application issues in the past few decades is summarized, including the two-phase de-tonation engine technology, short-distance and low-loss detonation initiation technology, perfor-mance optimization and prototype integration. For the two-phase detonation engine, researches on the velocity deficit in two-phase detonation and researches on the atomization and fuel-oxidizer mixing are introduced. Some new ideas are developed in recent years. To pursue a better propulsion performance, liquid fuel is pre-heated to improve the atomization performance. For the short-distance and low-loss detonation initiation, researches on the detonation initiation improvements using solid obstacles, fluidic obstacles, hot jet or shock focusing are involved. Employing solid obstacles is the most common technology used in the pulse detonation engine, whereas employing fluid obstacles can accelerate the detonation initiation with lower loss of propulsion performance. For the performance optimization, the partial filling effect, high efficient nozzles and high frequency operation technologies are discussed. Partial filling and proper nozzles are proved effective to enhance the propulsion performance, while more accurate theory is needed. Recent researches indicate that pulse detonation engines can reach a high operating frequency in the valveless mode. For the prototype integration, a few pulse detonation rocket engines launched by different institutions and the relevant experimental researches are introduced as well.