The numerical simulation on the flow field instability features of a variable thrust solid rocket motor

Variable thrust solid rocket motor will be wildly used in the future as the power unit for the divert/attitude control in the hypervelocity flight vehicles or spacecraft. In the thrust adjusting process, the disturbance wave is generated while the control valve rapidly switching. When the disturbance wave transmits in the pipeline, it makes the thrust fluctuate and affects the overall control effect. Therefore, it is necessary to probe the instability features of the switching process of the control valve. In the research, we have established three solid attitude control motor structures with different valve positions and the valve switching model. The instability features of the three different structures under the valve switching time of 1ms and 0.1ms were calculated and analyzed. The results showed that the gas impact velocity was relatively low and the response time of the thrust was relatively short while the valve is in the front of the convergent section. The response time of thrust could not be shortened by only accelerating the maneuver speed of the valve.