Experimental research on the characteristics of high-frequency pulse detonation waves in a high pressure chamber

The cycle frequency and combustion chamber pressure are the two key factors currently limiting the performance improvement of pulse detonation engines. To explore a reliable method for generating high-frequency pulse detonation waves in high-pressure chamber, the present work experimentally investigates the propagation characteristics of high-frequency detonation waves in a high-pressure detonation chamber, based on a valve-less, isolation-free mode. Contraction nozzles with choking throats were adopted to maintain the initial pressure in the chamber. According to the results, fully developed pulse detonation waves with frequency up to 80 Hz were obtained, while the chamber pressure was in the range of 4.9-7.0 bar, and the maximum contraction ratio of the nozzle should not exceed 2. The maximum frequency of the multi-cycle pulse detonation is affected by both the contraction ratio of the exit nozzle and the initial pressure of the chamber. The higher the contraction ratio, the lower the chamber pressure at which high-frequency detonation can be achieved. The maximum detonation frequency of the detonation tube with a contraction ratio of 2 does not exceed 40 Hz at 8.2 bar chamber pressure. It also indicates that the profile and length-diameter ratio of the convergent nozzle directly affect the frequency and stability of the high chamber pressure detonation, and the convergent nozzle based on the Vitoszynski curve is more conducive to improve the pulse frequency.