用N-S方程有限体积法计算弹体绕流/底喷流

Computation of flows around projectile bodies with base jet using finite-volume method of Navier-Stokes equations

用单元中心有限体积法在物理空间曲线网格离散积分形式N S方程,用坐标变换计算粘性通量项中的各偏导数值,用Runge Kutta三步显式格式进行时间推进求解。采用了人工粘性、当地时间步长及隐式残值光顺。计算了旋成体大迎角涡流和带底部喷流的绕流场。计算中发现,各向异性隐式残值光顺较之各向同性隐式残值光顺能更快地加速迭代过程的收敛。计算的物面压力分布与实验基本符合,计算的旋成体大迎角涡流图谱合理。计算结果说明底部喷流对旋成体绕流及空气动力载荷有显著影响。

The NavierStokes equations in integral form are discretized in physical curvilinear grids, and solved by RungeKutta threestage explicit timestepping scheme. The partial derivatives in viscous flux term are obtained by coordinate transformation. The artificial dissipation, local time step and implicit residual smoothing are utilized. It is found in computations that the anisotropic implicit residual smoothing is much better than the isotropic one in accelerating convergence. The computed body surface pressure distribution is in agreement with that of experiment in general. The calculated vortex structure in flows around projectile bodies at moderate to high angles of attack is reasonable. The computational results indicate that the subsonic, overexpanded supersonic base jets have certain effects on the flow and aerodynamic load over the body and the under-expanded supersonic base jets have significant effects on the flow and the aerodynamic load over the body. 