针栓变推力固体火箭发动机动态响应特性研究

为了解针栓式固体发动机的动态响应特性,基于可变等效喉部面积的调控内弹道模型,研究了针栓型面及其调节过程对发动机动态响应的影响。结果表明:针栓式变推力固体发动机响应时间以及推力响应的动态特性与针栓移动速度、针栓型面以及推进剂压力指数密切相关。发动机响应时间由针栓移动时间和针栓移动造成的压力延迟时间组成;随针栓移动速度增大,针栓移动过程与压力延迟过程相对比重发生变化,使得响应时间先快速缩短后趋向于定值,由32ms缩短至11.6ms,而推力过冲逐渐增大,但在针栓打开过程中响应时间更短,推力过冲更大,并且计算表明压力和等效喉部面积的相对变化率决定了推力过冲;随着正压力指数的增大,压力调节范围增大,推力过冲和响应时间均增加,而负压力指数的推进剂明显缩短响应时间,抑制推力过冲;凸型面针栓能够缩短响应时间同时降低推力过冲,可根据等效喉部面积相对变化率获得最佳型面曲率,使得响应时间和推力过冲最小。

Simulation on Dynamic Response Characteristics of Pintle Variable Thrust Solid Rocket Motor

In order to investigate the dynamic response characteristics of the pintle solid rocket motor, based on the adjustable internal elastic model with variable equivalent throat area, the influence of the pintle profile and adjusting process on the dynamic response characteristics of the motor was studied. The results show that the dynamic characteristics for the response time and the thrust response are closely related to the pintle speed, the pintle profile and the propellant pressure index, in pintle variable thrust solid rocket motor. The response time is composed of the time of pintle movement and the pressure delay time caused by pintle movement in the motor. With the increase of pintle speed, the relative proportion of the pintle movement and pressure delay process changes, so that the response time first decreases rapidly and then tends to a fixed value, from 32ms to 11.6ms, while the thrust overshoot increases gradually. During the opening process of pintle, the response time is smaller and the thrust overshoot is larger, the calculation shows that the relative variation rate of pressure and equivalent throat area determines thrust overshoot; with the increase of positive pressure index, the variation range of pressure increases, and the thrust overshoot and response time also increase. Compared with positive pressure index, the propellant with negative pressure index significantly shortens the response time and suppresses the thrust overshoot. The convex pintle can also reduce the response time and thrust overshoot at the same time. According to the relative variation rate of the equivalent throat area, the best curvature of the pintle can be obtained to minimize the response time and thrust overshoot.