Experimental investigation of air-breathing valveless pulse detonation engine

Revolutionary concept propulsion systems including air-breathing pulse detonation engine (PDE) are required in order to achieve high-speed cruise capability in the atmosphere. An air-breathing valve-less PDE model was designed and manufactured, which was made up of subsonic inlet, mixing chamber, ignition chamber, detonation chamber and nozzle. And the proof-of-principle experiments of PDE model were successfully carried out, by using liquid gasoline-air mixture with low-energy system (total stored energy less than 50 mJ). The air was supplied upstream of the air inlet by a semi free flow-field. A circumferential seam configuration collecting the inlet with mixing chamber was used to increase the mixing degree of gasoline/air and reduce the bad effect of air inlet on detonation initiation for detonation is difficult to initiate in the tube with two end open. The measured detonation wave pressure ratio was very close to that of C-J detonation. The air-breathing PDE model was easy to initiate and worked in good condition. The deflagration to detonation transition (DDT) and two methods to reduce DDT distance were also investigated. The results indicated the DDT distance was about 1.3 m (from the ignitor) and it was reduced to 1.09 m when the ignitor with higher energy was used. Compared to pulse detonation rocket engine (PDRE) with one end close and one end open, the evolution of pressure at different positions along the air-breathing model is more complicated with twice rising and twice falling.