旋翼气动力数值模拟准确度影响因素计算

针对旋翼气动力CFD计算时的一些常见影响因素的选择问题,进行了数值计算讨论.计算求解器选择自研代码,该代码采用基于共享内存(OMP)的并行化方法,在嵌套网格系统下求解Navier-Stokes方程,空间方向上使用2阶迎风格式,时间方向采用双时间方法.讨论的问题包括背景网格数目对悬停桨尖涡捕捉、对前飞状态激波捕捉和气动力的影响,远场动量理论修正作用对计算结果影响等.对于讨论的不同网格数目情况下,计算的悬停状态旋翼拉力差异在6%左右,扭矩差异2.6%左右,旋翼前飞阻力和扭矩最大差异为2.58%和3.28%.是否采用动量修正旋翼拉力相差3%~5%.通过计算,给出了针对以上因素计算结果差异的范围,可以为旋翼气动力计算工作提供一定的参考. 

Numerical study on the influence of some factors on results accuracy in rotor aerodynamic simulation

Numerical analysis for evaluating the effect of some common factors on rotor aerodynamics was conducted with an in-house CFD solver, in which a second-order upwind finite-volume and dual time-stepping scheme were used for Navier-Stokes equations discretization under an embedded grid system; and the numerical process was accelerated by OMP parallel technique.The involved problems mainly include the effect of background grid points scale on tip-vortex capture in hover, shock wave in forward flight and blade force, and the differences between the aerodynamics results obtained with/without 1D momentum far field boundary condition.The calculated rotor lift and torque discrepancy in hover are approximately 6% and 2.6% with different background grid points, and the drag and torque discrepancy in forward flight are 2.58% and 3.28% separately. The lift results show about 3%-5% difference with and without 1D momentum far field boundary condition correction.The fluctuation range of rotor aerodynamics with above-mentioned parameters was given by calculation, providing useful reference in rotor aerodynamics simulation.