Abstract
As part of the studies on the advanced solid rocket in JAXA, numerical simulations were carried out to investigate the effect of the flame deflector (FD) shape on the acoustic level of the launch vehicle at lift-off. The results indicate that there are mainly two types of acoustic sources; 1) “impingement noise” due to the interaction of the exhaust plume and FD, and 2) Mach wave generated by the flapping motion of the plume flowing over the FD. Since the impingement noise propagates directly to the vehicle, the acoustic level of the vehicle is dominated by the impingement noise. Based on the knowledge obtained here, it is found that the initial inclination angle of the FD should be steep to reduce the impingement noise. Besides, it also turns out that the FD is desirable to have a curved surface both for reducing the size of the FD and for preventing another impingement noise caused by the rapid change of the FD contour.
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