Semi-free-jet simulated experimental investigation on a valveless pulse detonation engine

• The semi-free-jet simulated ground experiments of a two-phase PDE were performed.
• The processes of pressure back-propagation were analyzed.
• The average thrusts of the PDE with different induction systems were compared.

The total pressure recovery coefficient, flow coefficient and intake resistance of a valveless pulse detonation engine (PDE) with five different induction systems were measured based on the semi-free-jet simulated ground experiments. The proof-of-principle experiments of pulse detonation engine mockup with above five different induction systems were all successfully carried out, by using liquid gasoline-air mixture with low-energy ignition system (total stored energy less than 50 mJ). The process of back-propagation of pressure and average thrust of PDE mockup with these different induction systems were compared. The results indicated that induction system 1 had higher performance in total pressure recovery coefficient, flow coefficient or flight resistance. The time interval (Δt) between the time of detonation initiation and the time of backward pressure perturbation propagating to the PDE inlet decreased gradually at the increased operating frequency. The average thrust of the PDE with induction system 4 was the highest in case of lower operating frequencies, while that of PDE with induction system 1 was the highest when operating at higher frequencies.