Characterization of Shock Wave Transfer in a Pulse Detonation Engine–Crossover System

Abstract

Shock wave propagation within a pulse detonation engine–crossover system is investigated, examining the properties and mechanisms of the transfer process. A shock wave is transferred through a crossover tube that connects a spark-ignited driver pulse detonation engine to a secondary, driven pulse detonation engine. Detonations in the driven pulse detonation engine develop from shock-initiated combustion, as strong shock wave reflection can cause ignition within a reactive mixture. A pulse detonation engine–crossover system can decrease deflagration-to-detonation transition length while employing a single spark source to initiate a system consisting of multiple detonation engines. Visualization of a shock wave propagating through a clear channel reveals a complex shock train behind the leading shock wave. Transverse waves connect with the leading shock wave to form a triple point that oscillates through the leading shock wave. The shock wave Mach number and decay rate remain constant for varying crossover tube geometries and operational frequencies. A temperature gradient forms within the crossover tube due to forward flow of high-temperature ionized gas into the crossover tube from the driver pulse detonation engine and backward flow of ionized gas into the crossover tube from the driven pulse detonation engine. This communication results in intermittent autoignition of the driver pulse detonation engine for higher-frequency large-crossover-tube-diameter cases. However, small-diameter crossover tubes prevent these autoignition events at higher frequencies.