联合使用激波捕获—拟合法求解激波间断的跨声速流场

吸取激波捕获和激波拟合两种方法各自的优点,发展了一种求解有激波的跨声速流场的方法,并对回转叶栅中定常跨声速流场做了计算。计算中,通过捕获法确定初始激波位置,然后经反复修正,拟合出确定的流场通道激波。计算表明,这种方法可自动获得清晰的激波,流场中气流各参数分布合理。这一方法可适用于复杂边界和不同进口M数,计算时间仅比势函数方法多一倍左右。

TRANSONIC CASCADE FLOW SOLVED BY THE COMBINED SHOCK-CAPTURING AND SHOCK-FITTING METHOD

A method for solving steady transonic flows has been developed which is a combination of the shock capturing and shock fitting methods. Such a combination takes full advantage of each of the two approaches.In the calculation, by use of the artificial compressibility and the AF2 scheme a full potential equation in divergence form with arbit-rary non-orthogonal coordinate system is used first to calculate the wh-ole blade-to-blade flow field and smeared shock wave is captured auto-matically as region of steep gradients in flow variables. Subsequently, the initial position of shock may be assumed from this region and its is employed as both the computational boundary line and the coordinate line. As boundary line, the flow variables across the shock, including the entropy increase on each streamline, are given according to the shock relations. As coordinate line, the calculating grids are rebuilt in the region behind the shock. The Kutta condition and the exit boundary conditions are modified in order to allow for the effect of entropy variation, and the non-isentropic potential equations are utilized to the flow after the shock. A criterion is given to examine if the location and shape of the shock are correct. In case the criterion is not satisfied, the position of the shock will be adjusted based upon this criterion and the next cycle will be performed repeatedly until a convergent solution is obtained.