Underwater thrust characteristic of solid rocket motor

The underwater performance characteristics of solid rocket motors (SRM) are different from those in the air as they are surrounded with high density medium water. In order to have a deep understanding into the performance characteristics of underwater SRM, the impact of the change of the flow structure on thrust was analyzed. A 2-D axial symmetry model was adopted to simulate underwater SRM in different working conditions, and the figures of thrust oscillations were obtained. After analyzing the changes of thrust in different stages, the relationship of thrust peak value and neck breaking was studied, and the thrust oscillation amplitude and frequency changing with working environment were studied. The research results show that the thrust oscillation occurs due to the periodic neck breaking induced by the shock wave. In addition, as a result of the action of gas bulge and back-attack, the jet thrust takes on a multistage frequency and peak value. According to the conclusion that the bulges are in the middle-frequency band, researches on the first four order frequency show that the gas bulge is related to the back attack.