Effect of heat loss on pulse-detonation-engine flow fields and performance

The present study addresses the influence of convective heat losses on the flowfield and performance of pulse detonation engines (PDE). We investigate the simplest PDE configuration of a single-cycle straight detonation tube open at one end. The gasdynamics: are modeled by a simple one-dimensional formulation and solved by the method of characteristics. Previous heat-flux measurements obtained in hydrogen-air and hydrogen-oxygen detonation experiments are used to calibrate the convective heat-flux model. The results are compared with previous experiments in hydrogen, propane, and ethylene mixtures with either oxygen or air. The present model is found in very good agreement with experiment and reveals how the influence of heat losses is manifested on the pressure profiles inside the detonation tube. It is shown that the nondimensional tube length L/D, where D is tube diameter, governs the amount of losses; the rate of pressure decay at the thrust wall, and hence the specific impulse. The present study reveals that the specific impulse losses vary quasi-linearly with L/D, reaching a deficit of approximately 20% in tube geometries of L/D = 50.