Determination of the effect of frequency and spark timing on the thrust using a lab-scale pulsed detonation engine

An experimental study was performed on an ethylene-oxygen-air pulse detonation engine (PDE) to examine the effect of frequency and spark timing on the thrust output and efficiency. Dynamic pressure measurements were recorded throughout the system over the testing interval to determine exhaust velocities. Multiple scripts were programmed to evaluate the raw data from the experiments to determine instantaneous velocity, thrust, and frequency. Efficiency was evaluated based on the experimental average frequency and the experimental average velocity. Results on experimental thrust, detonation frequency, and Chapman-Jouguet velocities were analyzed. It was determined that for a spark delay time of 2 ms, maximum efficiency and thrust were achieved for given frequencies. As spark delay time increased beyond 6 ms, testing became erratic, with pulses misfiring and a decrease in efficiency and thrust was observed until no combustion occurred beyond a spark delay time of 8 ms.