惯性颗粒在非均匀加速流中的输运问题

Inertial particle transport in non-uniform accelerated flow

基于新型碳基颗粒增强或碳基纤维材料的再入体热烧蚀问题对飞行器的气动力/热性能影响机制尚不明确。初步研究不考虑化学反应和气体引射效应,把热烧蚀问题中的颗粒剥离问题模化为驻点流中的离散颗粒启动问题。由于高速气流在驻点温度达上万度量级,局部马赫数接近于0,研究近似假设靠近壁面的流体动力学为不可压缩的,并使用不可压缩颗粒解析的直接数值模拟方法(PR-DNS)研究一个惯性颗粒在平面挤压流和壁面驻点流中的动力学,从而揭示在驻点流中的颗粒输运机制。研究发现颗粒在壁面驻点流中的输运机制是水平输运,几乎没有垂直输运,与平行剪切颗粒床输运非常不同,这是驻点流特有的垂直向下挤压作用导致的。

The effect of thermal ablation of novel carbon fiber composites material on the aerodynamic force and heat is not fully understood.As the primary research,without considering the chemical reaction,gas injection and other complicate physical process,this study assumes the particle loss from the vehicle surface as a discrete particles dynamics problem.Because of the high temperature in the near wall,and that the local Mach number is vanishingly small,so the near wall fluid flow can be treated as incompressible.Thereby,Particle Resolved Direct Numerical Simulation(PR-DNS)of incompressible flow is used to study the particle dynamics in a strain flow and wall-bounded stagnation point flow.It is found that the particle transport in a wall-bounded stagnation point flow is horizontal,with minimal vertical transport,which is very different from that of parallel shear flow over a particles bed.This is due to the normal hydrodynamic force of stagnation point flow.