三维跨音速流有限差分计算中的某些问题

一、基本方法简介 1.三维跨音速小扰动方程 柱坐标下的三维跨音速小扰动方程为

SOME PROBLEMS IN THE FINITE-DIFFERENCE COMPUTATION OF THREE-DIMENSIONAL TRANSONIC FLOWS

The mixed finite-difference relaxation iteration method is applied to calculation of the wing-body combination with rectangular wings based on the three-dimensional transonic small-disturbance potential equation in the cylinder coordinates. Meanwhile, the influences of different computation regions and relaxation parameters （on subsonic points） on the ranges of the computed Mach numbers, angles of attack and calculated results are studied.It is shown that extending the computation region brings about increasing the convergence range of the small-disturbance equation, and the convergence rate and computation accuracy would be are enhanced if the subsonic relaxation parameter is taken to be 1.9.Also, it is demonstrated that the calculated results differ when the finite or infinite region is taken as the computation region of the r-direc-tion. Particularly the distribution of the pressure cooeficients near the wingtip varies obviously as the incident Mach number becomes larger.