基于多物理场耦合的双脉冲发动机点火过程数值模拟

Numerical simulation of the ignition transient of dual pulse motor based on multi-physics coupling

为研究双脉冲固体火箭发动机Ⅱ脉冲点火瞬态过程,发展一套多物理场耦合求解器。流体控制方程基于有限体积法求解,时间推进采用双时间步LU-SGS(Lower Upper Symmetric Guass Seidel)方法;固体推进剂表面温度基于耦合传热方法计算;结构动力学运动方程基于有限元方法离散,采用经典的Newmark格式进行时间推进,流固耦合采用松耦合算法,并通过算例验证求解器的可靠性。计算结果表明:该求解器能够数值模拟Ⅱ脉冲启动过程中的点火药气体冲击、燃气非定常流动及金属膜片机械响应过程,获得金属膜片的破裂时间和压强;且随着点火质量流率增加,推进剂装药首次点燃时间和金属膜片破裂时间变短,膜片破裂压强降低;金属膜片破裂时间和压强不仅与作用在其表面的压强载荷大小相关,而且与压强载荷加载的过程相关;金属膜片厚度越薄,膜片破裂时间越短,膜片轴向位移越大,膜片破裂压强越低。

In order to study the second pulse ignition transient of a dual pulse solid rocket motor,a multi-physic solver is developed.The governing equations for unsteady compressible fluid flow are solved with dual time LU-SGS（lower upper symmetric Guass seidel）iterative algorithm by finite volume method.The conjugate heat transfer strategy is employed to calculate the propellant surface temperature.A finite element method is used to discretize the structural dynamic equation in space,whereas the temporal time integration is achieved with the classic Newmark algorithm.A loosely coupled algorithm is used for fluid structure interaction problems,and the reliability of the numerical approach is validated by a comparison with experimental cases.Results show that the multi-physics solver can simulate the impact of ignition gas,strong unsteady flow,and mechanical response of metal diaphragm.The burst time and burst pressure of metal diaphragm can be also acquired.Meanwhile,with the increase of the ignition mass flow rate,the first ignition time of propellant and the burst time of the diaphragm become shorter and the burst pressure of the diagram decreases.The burst time and burst pressure of metal diaphragm are not only related to the pressure load on the surface of diaphragm,but also to the history of the pressure load on it.With the decrease of thickness of metal diaphragm,the burst time of the diaphragm goes shorter,the burst pressure of diaphragm decreases,and the maximum horizontal displacement of the diaphragm increases.