用强耦合RANS方法模拟旋翼悬停流场

在旋转坐标系下,将Spalart-Allmaras(S-A)一方程湍流模型和Reynolds-averaged NavierStokes(RANS)方程耦合成一个新的RANS方程,并发展了基于多块重叠网格的强耦合RANS求解方法,用于直升机旋翼悬停流场的数值模拟.为了提高计算效率,针对多重网格方法在多块重叠网格上实施的困难,提出了一种基于重叠网格的多重网格实施方法.通过对Caradonna-Tung(C-T)和ONERA 7A旋翼悬停算例验证了发展的强耦合RANS方法和基于重叠网格的多重网格实施方法的有效性.研究结果表明:发展的基于重叠网格的多重网格方法有较高的计算效率,3层网格的加速比约为7.7;强耦合RANS法的计算精度明显高于传统的松耦合RANS方法,特别是在与阻力相关性能参数的预测中,强耦合RANS方法的预测结果更加精确.

Strongly coupled RANS algorithm for simulating hovering rotor flow

In the rotating coordinate system, Reynolds-averaged Navier-Stokes (RANS) equations and Spalart-Allmaras (S-A) equation model were coupled as a new strongly coupled RANS equation, then a strongly coupled RANS algorithm based on overlap grids was proposed and applied to simulate helicopter rotors viscous flow in hover. In order to improve efficiency, a new implementation method of multigrid algorithm based on overset grids was proposed for solving the difficulty of implementation in chimera grids system. The effectiveness of strongly coupled RANS method and the proposal of multigrid algorithm based on chimera grids was verified using Caradonna-Tung (C-T) and ONERA 7A hover test cases. The results show that the proposal of multigrid algorithm based on overlap grids has much higher efficiency, and the speed up ratio of three-level multigrid is about 7.7; the accuracy of strongly coupled RANS algorithm is super higher than loosely coupled RANS algorithm, especially in the prediction of performance parameters relevant to drag force.