Unsteady flow around a concave body in supersonic flow

高速飞行器进入行星大气层时，需要采用各种方法进行减速。最有效的空气动力学减速系统之一是降落伞，在体积很小的情况下使用，当然也可以施加阻力。但是，由于它的灵活性，这是一个非常复杂的现象。在本研究中，数值模拟主要用于分析流场的特征。采用TVD格式求解三维非定常全Navier-Stokes方程。同时，用摆运动方程分析了物体的振荡。指出了降落伞对凹体流体“溢出”和激波干扰的重要性，并在早期指出了波状分布激波的发展。此外，还指出了虚质量对流场的重要影响、振荡体与尾流的非线性相互作用等。在不久的将来，降落伞的充气过程和流场的发展需要同时完美地解决，这表现出很强的非线性。在捕捉到这些现象后，我们可以为设计新的降落伞提供准确的数据。

It is necessary to decelerate by using various methods when the high speed vehicle entry into the atmosphere of the planet. One of the most effective, aerodynamic deceleration systems is the parachute, and has been used in the point that volume could be small, and that the drag can certainly applied. But, it is a very complex phenomenon for flexibility of it.In this research, the numerical simulation is applied mainly to analyze the feature of flow field. The 3-dimensional unsteady full Navier-Stokes equations are solved by using the TVD scheme. Also, the body oscillation is analyzed by the equation of the pendulum motion.The parachute would be pointed out the feature of the importance of the interference with "Overflow" of the fluid from the concave body and the shock wave, while the development of the wavy distributed shock wave is pointed out in early stage, too. Moreover, the important effect of the virtual mass on the flow field, the non-linear interaction of the oscillating body and the wake flow and so on are pointed out.In the near future, both the inflating process of the parachute and the development of the flow field should be solved simultaneously in perfect, which shows the very strong non-linearity. After catching the phenomena, we could propose the accurate data to design the new parachute.