用于弹性旋翼流场模拟的网格变形方法

摘要

To provide a solution of analyzing the influence of elastic deformation on the rotor blade-fitted grid based on an improved "Ball-Vertex" spring simulation, a topology-unrelated grid deforming method is developed to simulate the blade-fitted grid movement and the near-rotor flowfield.Based on the spring simulation, the method uses a spring net to model the deformation and the movement of the blade-fitted grid.By introducing the "Ball-Vertex" concept and adopting the necessary constraint springs, the new grid deforming method can assure that the grid vertex can not across its diagonal planes to avoid abnormal grid ceils.It is suitable for fairly large deformation cases.As a numerical example, the method is firstly used to simulate the deformation of the 2-dimensional structured and unstructured grids around a typical airfoil with translated and rotated movement, and its capability is demonstrated.Then, the grid method is combined with computational fluid dynamics (CFD) and used to calculate the loads of oscillating airfoil for further validation.Finally, the method is coupled with the rotor CFD and the flowfield simulation of the elastic rotor is carried out.Based on the above research, some meaningful conclusions are drawn.%建立了一个基于改进"Ball-Vertex"的具有拓扑无关性的网格变形方法,用来精确模拟桨叶发生弹性变形后贴体网格的运动以及旋翼近场气动力环境,为更好地分析弹性变形对桨叶贴体网格的影响提供了一套解决方案.该网格变形方法从基本的弹簧模拟思路出发,用一网状弹簧系统来模拟桨叶贴体网格的变形和运动.在网格结点周围引入"Ball-Vertex"概念,通过添加相关的冗余约束,该方法保证网格结点在变形过程中不会越过与该点所对应的对角面,从而避免了畸形网格单元的产生,可有效地用于较大变形情况下的流场数值计算.使用所建立的方法,首先对绕二维翼型的结构网格和非结构网格进行了网格变形模拟,以表明方法的有效性;然后,将该方法应用于振荡翼型的流场数值求解,进一步验证了所建立的方法;最后,结合该网格变形方法和旋翼流场求解方法对弹性旋翼流场进行了数值计算.在此基础上,得出了一些有意义的结论.