用隐式近似因子分解法计算喷管跨音速流场

THE COMPUTATION OF TRANSONIC NOZZLE FLOW BY AN IMPLICIT APPROXIMATION-FACTORIZATION ALGORITHM

关键词:  喷管  跨音速流  流场  数值解  计算

Key words:  Nozzle  Transonic flow  Flow field  Numerical solution  Computation

摘要:

本文用隐式近似因子分解法结合贴体曲线坐标计算了定常、无粘、跨音速喷管流场,选择了参数变化比较剧烈的小喉部曲率半径喷管,陡壁收敛段喷管和潜入喷管三种算例.计算结果表明,该方法收敛快,并且具有良好的精度.Courant数可以取至7.这种隐式法与显式法相比较,花费的机时少得多.本文的方法可望推广到求解N-S方程、PNS方程,和二相有粘喷管流动计算.

Abstract:

At present, the time dependent method has been widely used to predict transonic flow fields in solid rocket nozzles. The difference form of this method is explicit one which consumes excessive computational time because of the time steps limited by the stability criterion. Recently, the implicit form has been paid much attention. Beam, R.M.and Warming, R.F. presented an implicit approximation-factorization algorithm of Euler equation. Time steps longer than those requested in explicit form can be often taken.In this paper, the implicit approximation-factorization algorithm with the boundary-fitted coordinates system is applied to calculate steady inviscid transonic flows in nozzles. Three different nozzles which consist of throat with small curvature radius, steep convergent portion and submerged portion and therefore which parameters are changed seriously-are calculated. The good agreement of the computational results with experimental ones shows that the method is of good convergence and good accuracy. Due to the use of explicit form at the boundaries,Co-urant number is still limited to a certain degree, which is taken up to about 7 for the implicit procedure presented in this paper. This method can greatly accelerate the computation process and can be efficiently extended to tfae computations of N-S equation, PNS equation and viscid two-phase flow for solid rocket nozzles.