特征线坐标系下柱对称超音速流膨胀波计算方法研究

在静压圆盘止推气体轴承柱对称超音速流膨胀波系的计算中，借鉴Liepmann的特征线坐标系与自然坐标系变换理论和Liepmann引入两个黎曼不变量的方法，使得边界条件的处理更为直观和简便。采用特征线坐标系下的特征线法，推导计算该膨胀波系所用到的基本计算公式，将其应用于 P-M 流动并与 P-M 流动理论解进行比较。结果表明，数值计算结果与P-M流动理论解吻合，该计算方法可行。

Method for calculating the expansion wave in cylindrical symmetry supersonic flow under characteristics line coordinates

In cylindrical symmetry supersonic flow of circular gas bearing ,curve expansion wave will be produced from the turning point of evagination bearing wall .By using Liepmann’ s transformation theory of characteristics line coordinates with the natural coordinate as well as two Riemann invariants introduced by Liepmann ,treatment of the boundary conditions is more intuitive and convenient .The basic formula for calculating the expansion wave is deduced with characteristics method under the characteristic line coordinates .When the method is applied to the P-M flow ,the numerical results agree with the theoretical results of the P-M flow ,which suggests that the calculation method is effective .