高空状态下高超声速乘波飞行器气动性能模拟

Aerodynamic Performance Simulation of Hypersonic Waverider in Near Space

运用以分子动力学为基础的直接仿真的蒙特卡罗（DSMC）方法,发展了临近空间飞行器气动性能模拟软件系统。以某型航天飞机再入大气层为例,验证了系统的有效性。对乘波构型飞行器在高度为70-100 km的临近空间区域的气动性能进行了模拟,研究了稀薄气体效应对高超声速乘波构型气动特性的影响。由于70-100 km的临近空间区域处于连续介质区与温度和速度跳跃区,在DSMC的模拟中为避免模拟陷于大量的分子碰撞计算,对DSMC算法的碰撞模型和有效碰撞次数进行了改进。研究结果表明：在临近空间区域,乘波构型的升阻比特性略有下降,但仍旧保持了高升阻比的气动优势;DSMC模拟结果与NS方程模拟结果随着高度增加,两者差距逐渐增大,稀薄气体效应逐渐显著;DSMC方法的模拟中,经过多次计算,最终确认在每个网格区域内15次有效碰撞次数足以模拟气体的宏观物理特性。

Aerodynamic performance simulation software system of hypersonic waverider vehicles in near space was developed by using the direct simulation Monte Carlo（DSMC） method based on molecular dynamics. Taking a certain aerocraft as an example, the effectiveness of the system was verified. Aerodynamic performances of the vehicle at the height of 70- 100 km in near space were simulated, the influence of rare gas effect on aerodynamic performance of the vehicle was studied. Collision model and effect collision number of the DSMC method were improved, in order to avoiding a large amount molecule collision calculation caused by DSMC simulation in continuous medium district and jumpiness district between temperature and velocity at the height of 70 - 100 km in the near space. The studied results show the characteristic of lift-to-drag ratio of the vehicle descends in near space, but it remains high lift-to-drag aerodynamic advantage; the difference of simulation results between the DSMC and NS equation increases with the height increasing and the effect of rare gas increases gradually; it is proved that fifteen effect collision number in every grid is enough to simulate the macrophysical characteristic of air in DSMC method.