用鲁棒Riemann求解器和运动重叠网格计算旋翼粘性绕流

发展了一种基于鲁棒Riemann求解器和运动重叠网格技术计算直升机悬停旋翼流场的方法。基于惯性坐标系,悬停旋翼流场是非定常流场,控制方程为可压缩Reynolds平均Navier-Stoke方程,其对流项采用Roe近似Reimann求解器离散,使用改进的五阶加权基本无振荡格式进行高阶重构,非定常时间推进采用含牛顿型LUSGS子迭代的全隐式双时间步方法。为实施旋转运动和便于捕捉尾迹,计算采用运动重叠网格技术。计算得到的桨叶表面压力分布及桨尖涡涡核位置都与实验结果吻合较好。数值结果表明:所发展方法对桨尖涡具有较高的分辨率,对激波具有较好的捕捉能力,该方法可进一步推广到前飞旋翼粘性绕流的计算。

A robust Riemann solver and moving overset grids for viscous flow computation of rotors

A numerical method has been developed to simulate the flow fields around helicopter rotors in hover with a robust Riemann solver and a moving overset grid technique.In the inertial coordinate system, the governing equations are Reynolds averaged Navier-Stoke equations for the unsteady flow fields around hovering rotors.Convective terms are discretized by the Roe approximate solver based on a fifth-order weighted essentially non-oscillatory scheme.A full implicit dual-time stepping method with the Newton type LU-SGS sub iteration is adopted for the unsteady time advance.The moving overset grids are used to enforce rotation and capture wake.The surface pressure coefficients of the hovering rotor blade and the tip vortex core positions accord with the experimental data.The numerical results indicate that the present method has high resolution for tip vortices, and can well capture shock.So the method could be further developed to compute the viscous flows around rotors in forward flight.