带副翼偏转的三角翼自由滚转运动数值模拟

 通过耦合求解非定常Euler/Navier-Stokes方程和单自由度滚转运动方程,对带副翼偏转的65°后掠角尖前缘三角翼WI1-SLE自由滚转运动进行了研究,Navier-Stokes方程的求解采用基于Spalart-Allmaras湍流模型的脱体涡模拟(DES)。在多块结构网格上,应用基于弧长的无限插值理论(TFI)生成变形网格,实现副翼偏转,而三角翼的滚转运动则通过网格的整体旋转实现。结果表明:Euler方程和DES方法均准确地模拟出了三角翼在滚转运动过程中存在的3个平衡位置。出现平衡位置的原因分别是:①流动对称性;②机翼左侧发生涡破裂的分离涡与右侧分离涡相互平衡使得滚转力矩为0,并且平衡位置仅与三角翼两侧涡强的差有关;③副翼偏转和左右机翼不对称分离涡涡强差产生的滚转力矩相互平衡。此外,滚转运动对副翼偏角幅值很敏感,幅值的微小改变会影响最终的平衡位置和向平衡位置运动的路径。     

RBFs-MSA Hybrid Method for Mesh Deformation

Simulating unsteady flow phenomena involving moving boundaries is a challenging task,one key requirement of which is a reliable and fast algorithm to deform the computational mesh.Radial basis functions(RBFs) interpolation is a very simple and robust method to deform the mesh.However,the number of operations and the requirement of memory storage will be increased rapidly as the number of grid nodes increases,which limits the application of RBFs to three-dimensional(3D) moving mesh.Moving submesh approach(MSA) is an efficient method,but its robustness depends on the method used to deform the background mesh.A hybrid method which combines the benefits of MSA and RBFs interpolation,which is called RBFs-MSA,has been presented.This hybrid method is proved to be robust and efficient via several numerical examples.From the aspect of the quality of deforming meshes,this hybrid method is comparable with the RBFs interpolation;from the aspect of computing efficiency,one test case shows that RBFs-MSA is about two orders of magnitude faster than RBFs interpolation.For these benefits of RBFs-MSA,the new method is suitable for unsteady flow simulation which refers to boundaries movement.     

多块协调变形的网格变形技术及其应用

基于多块网格协调变形的理论,提出了适用于叶轮机内流多物边界的更具一般性的网格变形技术,先获得块边界处的变形量,然后插值得到块内网格各点的变形量。通过二维振荡叶栅和带叶尖间隙的三维跨音风扇叶片的非定常绕流算例,证明网格变形技术在叶轮机气弹稳定性数值模拟中的应用是有效的,能够在保证网格高精度的条件下,提高网格变形速度。