Parametric Study of Laser Energy Deposition in Mach 8 Bow Shock

摘要

A numerical study was performed to investigate the effect of laser energy deposition in a Mach 8 bow shock. The computational model was extracted from the experiment in which a nominal two-dimensional Mach 8 flow over a cylinder with diameter of 76 mm was studied. The surface pressure was in good agreement with experiments, and the standoff distance agreed well with the theoretical value. The process of blast wave propagation and bow shock distortion was analyzed for energy deposition. The effect of energy level, deposition location and pulsing frequency was studied. For a single pulse of energy deposition, results showed that the reduction of the time-averaged surface pressure increases beyond certain energy level, while the deposition location had less effect on the time-averaged pressure. For a continuously pulsed deposition, the surface pressure in the stagnation region was reduced with increase of frequency. A33% pressure reduction was achieved with a frequency of 100 kHz. The envelop of the blast wave formed a conically shaped shock wave in front of the blunt body, resulting in the reduction of the wave drag.