阻力伞流场数值模拟

THE NUMERICAL SIMULATION OF PARACHUTE FLOW FIELD

运用非定常Navier-Stokes(N-S)方程有限体积算法及非结构动网格技术对X-37B飞行器着陆流场进行数值模拟,比较了飞行器在拖挂阻力伞和不拖挂阻力伞两种情况下的流场差异.模拟以混合网格有限体积方法为基础,控制体方程采用N-S方程组,流场计算空间离散采用格点格式,通量计算格式采用Roe,时间离散采用LU-SGS理论和二阶时间精度的双时间步长,湍流模型采用两方程SST湍流模型.动网格技术采用线性弹簧理论处理阻力伞在摆动时流场的变化.阻力伞模型采用中间带气孔的C-9圆锥型降落伞外形,但规模有所缩小,以便适应飞行器.模拟比较了两种情况下着陆流场的差别,并主要比较了两种情况下阻力的差别,从而证明飞行器在拖挂阻力伞的情况下更容易减速着陆.

A numerical simulation of X-37B landing flow field is implemented using the unsteady Navier-Stokes（N-S） control equations finite volume scheme and the unstructured ynamic mesh. The simulation compares the differences between the flow fields of the craft withand without a parachute.The simulation is based on a hybrid/unstructured finite volume method using the Navier-Stokes equations. Spatial discretization uses Median-Dual Cell- Vertex Scheme. Convective fuxes are computed using Roe Riemann solver. Temporal dis- eretization uses LU-SGS Scheme with 2rd order time-accuracy dual-time stepping method. For turbulent flows, the two-equation Menter＇s SST model are available. The unstructured dynamic mesh uses liner spring method to compute the flow field when the parachute swings. A model of C-9 pyramid parachute is used in this simulation. It is shrinked to fit the X-37B craft. The simulation compares the differences of flow field between the two cases and mainly compares the drag differences to prove the craft with a parachute easily landing.