Numerical Study of Pipeline Distribution Effect on the Performance of Pasty Propellant Rocket Motor

This paper reports the numerical research on PPRM (pasty propellant rocket motor) through computational fluid dynamics simulation along with pipeline design comparison based on simulation results. The structure of PPRM includes feed pipelines, and the propellant is distributed in a cone shape when burnt steadily in the combustion chamber. As a result, the internal flow field presents strong 3-dimensional characteristics, which may lead to the flow instability. To accurately understand the combustion flow field and flow instability in the PPRM, a numerical simulation of the combustion chamber considering propellant pyrolysis and chemical reaction, coupled with the feed system module, is employed in the research. The effect of pipeline distribution, including the pipeline location and the nonuniformity of pipeline diameter on the internal combustion flow characteristics as well as the motor thrust, was investigated. The results show that the vortex caused by the special conical shape of the burning surface leads to pressure oscillations. By adjusting the pipeline location and the nonuniformity of pipeline diameter, the distribution of vortex varies dramatically, which leads to different oscillation frequencies and amplitude. Under some pipeline distribution schemes, there is almost no large vortex in the rocket motor, which greatly eliminates the flow acoustic coupling oscillation of the motor. The oscillation amplitude decreases from about 5.7% to less than 0.1%. The results will help guide the design of the high-performance feed system and combustion chamber of PPRM.