非定常欠膨胀射流的正格式数值模拟

Numerical Simulation of Unsteady-State Underexpanded Jet Using Positive Schemes

采用二阶正格式方法对非定常欠膨胀射流进行了数值模拟。将二维守恒方程的正格式方法推广到轴对称Euler方程组的求解,并对不同马赫数下的燃气射流进行了数值计算。计算结果表明,该方法能够较好地捕捉到包含膨胀波、入射激波、反射激波、马赫盘、射流边界以及三波点等复杂射流流场的波系结构,与实验照片反映的流动特征以及已有的数值结果相吻合。表明该方法对间断解具有较强的捕捉能力,在激波阵面上不会出现数值振荡。

A numerical simulation of unsteady-state underexpanded jet was carried out using second order positive schemes,which was developed to solve the axisymmetric Euler equations based on two dimensional conservation laws.Computational results indicate that the method can capture the wave structures of jet flowfields including expansion fan,incident shock,reflected shock,Mach disk,jet boundary and the triple point well.Agreements between the numerical results and experimental or existed numerical results are fairly satisfactory.It indicates that the present method has high capability in capturing shocks without numerical oscillation near discontinuous points.