Dynamic combustion and response characteristics of a novel combined solid rocket motor regulated by a pintle valve

Thrust regulation has been a major challenge to the solid rocket motor. The dynamic combustion and response characteristics of a novel combined solid rocket motor regulated by a pintle valve are numerically studied in this paper. A two-dimensional transient combustion model of the combined motor is established. The results show that as the flow regulation ratio increases, the species mixing in the combustion chamber is greatly enhanced. The combustion zone moves towards the burning surface, which enhances gas-solid heat transfer and leads to larger regression rate. With the movement of the pintle valve, the flow and combustion processes near pintle valve and pre-combustion chamber are strongly intensified. Meanwhile, the zone with the best mixing effect moves towards the burning surface, which causes the regression rate to increase from 4.96 mm/s to 13.03 mm/s with movement of the pintle valve from 0.70 s to 0.76 s. With the flow regulation ratio increasing from 1.6 to 4.0, the response time of pressure decreases by 50 % while the regulation ratios of the thrust and the regression rate reach 3.35 and 2.11, respectively. When the regulation ratios increase, the average heat release rate gradually increases as the increase of the regulation ratio intensifies the mixing and oxidation reactions between the species. In addition, during the full-scale flow regulation of the oxidizer-rich gas, the specific impulse efficiency ranges from 81 % to 88 %. It is found that there exists an optimum regulation ratio to obtain the maximum specific impulse efficiency. Based on the results, it is possible to regulate the regression rate and the thrust of the combined solid motor simultaneously. This work provides better insight into dynamic combustion and response characteristics of solid motor under flow regulation.