钝锥大攻角超声速分离流场的数值模拟

最近,张涵信等人在传统的Beam-Warming隐式、无迭代、空间推进技术的基础上,根据边界层方程的性质,设计了一种可用小步长推进求解抛物化NS(PNS)方程、而不会引起解的“漂移现象”发生的方法。这种方法对轴对称流动的计算是成功的。本文就是将这一思想推广应用于大攻角有周向分离的流场计算。求解的区域为具有薄亚声速层的有粘与无粘干扰的整个激波层内的流场。在对攻角α=0°和α=20°的球钝锥的计算中,关于壁面上的压力、热流率及流场的涡旋结构均得到了满意的结果。文中特别研究了钝锥大攻角绕流的流动分离图象。 为了增强块三对角矩阵的主对角优势,通常在差分方程的左端附加二阶增量项。本文以选取适当小的推进步长的方法来达到增强主对角优势的目的,不需再附加二阶增量项,从而提高了解的精度。

NUMERICAL SIMULATION OF SUPERSONIC SEPARATED FLOW OVER BLUNT CONES AT HIGH ANGLES OF ATTACK

Through a study for the properties of boundary layer equations, a space-marching technique for solving parabolized Navier-Stokes (PNS) equations has been developed by Zhang recently, and the axisymmetrical flows over blunt cones have been simulated successfully. In the present paper, the above technique is extented to the calculations of flow fields with cross flow separation at high angles of attack using Beam-Warming implicit difference scheme. The calculated region is the flow field with thin subsonic layer and viscoursity. Satisfying results for blunt cone at high angle of attack are obtained. Special attention is paid to the separated flow pattern at high angle of attack.