一种用于TSTO级间分离CFD计算的网格动态优化技术

A mesh adaptation method for TSTO stages separation CFD simulation

两级入轨空天运输系统具有难度较低和经济性好的优点,级间分离是该运输系统设计的一项关键技术。相比前后串联级间分离,两级入轨上下两级间存在严重的激波相互干扰,直接影响分离物体的气动力矩。为了更好地模拟分离过程中两级之间的运动激波多次反射问题,本文结合非结构混合网格分布优化技术和压力比值激波识别技术,建立了用于级间分离运动过程的并行网格动态优化技术。基于计算流体力学软件NNW-FlowStar,完成了两级入轨运输系统并联分离过程的数值模拟。结果表明,采用网格动态优化技术,可实现级间复杂激波的精细捕捉,更精准地获得了强干扰下飞行器的气动特性,显著提高了并联分离过程中运动轨迹和姿态的预测精度。

The transport system of two-stages-to-orbit(TSTO)has many advantages,such as easy to implement and much less expensive.Successful separation between the two stages is a critical issue to design a TSTO transport system.Compared to a regular concatenation configuration with the front and back in-line layout,there is serious shock interference between the two stages of the TSTO parallel configuration,which obviously changes the aerodynamic moment of stages and consequently affects the attitude of upper stage during the separation procedure,such as the pitch angle.In order to simulate the multiple reflections of the moving shock wave between two stages in the separation process,a parallel mesh dynamic optimization technique for the separation process is established by combining the unstructured hybrid mesh distribution optimization technique and the pressure ratio based shock wave identification technique.The whole separation procedure was numerically simulated using the general computational fluid dynamics(CFD)software NNW-FlowStar.The results show that with mesh adaptation techniques,the complicated shocks between the two stages can be precisely captured,the more accurate aerodynamic moment can be obtained by CFD and hence the prediction precision of the trajectory and attitude can be improved significantly.