Research on thrust fluctuation characteristics of underwater solid rocket motor

The dynamic property of underwater solid rocket motor was studied in this article. Utilizing dynamic grid and the VOF principle, an axisymmetric model describing the dynamic response of the fluidic thrust of underwater solid rocket was established. Movement of the motor was successfully simulated based on the principle of surface integral and the computational method of underwater motor's thrust. By simulating motors under different cases using the dynamic model, the jet structure of underwater motor was studied. It turn out that the jet gas is extruded by the flow in the boundary layer, and generated necking phenomenon, and then expanded outward gradually. The results indicate that the shock wave produced by the jet will refract several times before going downstream, which is consistent with experimental results of other literature. The thrust's pulse peaks in different cases, were analyzed, and the change law of the features of underwater motors with the variation of environment was obtained. Finally, the dynamic characteristics of motors in conditions with/without buoyancy were compared and analyzed.