大斜度四面体网格在高升力构型中的应用

High skewness tetrahedron meshes and its application on high lift configuration

采用全四面体网格划分方法,基于格心有限体积离散求解三维可压缩雷诺平均N-S方程,数值模拟了梯形机翼高升力构型低速绕流流场。为了模拟粘性效应,物面附近采用层推进方法生成了大伸展比边界层网格,围绕网格斜度过大的问题,探讨了流场变量梯度和斜率限制器的计算方法,使计算格式既符合网格特点又满足精度要求。流动假设为全湍流,湍流模型采用S-A一方程模型,计算采用了基于消息传递(MPI)的并行分区计算方法,并行分区边界满足流通量守恒。通过对梯形机翼高升力构型标模算例的计算表明,计算的升阻力、力矩特性和载荷分布与试验数据吻合较好,不足之处是存在翼尖涡数值耗散过大的问题,影响到翼尖区域压力分布的预测精度。在攻角α=11.02°下采用了三种规模网格(网格单元从466万到2674万)对比计算研究网格收敛性质,结果表明随网格密度增加计算值更接近试验值,但收敛曲线不是随网格指数线性变化,反映了该流动问题的复杂性。

Structured grids are hard to be generated on high lift configuration of transport airplanes due to geometry irregularity, unstructured grids have the chance of optimizing local mesh quality and timesaving with strong adaptability and automatism in grid generation. With tetrahedron grids and cell centered finite volume discretization, solutions on a trapezoidal three-element high-lift wing obtained with an 3D compressi- ble Reynolds averaged Navier-Stokes code are presented. High aspect ratio meshes are formed by advancing layer methods to simulate viscous effect in boundary layer, surrounding high aspect ratio difficulties, meth- ods of solution gradients reconstruction and slope limiters are discussed, and accurate and affordable schemes for current grids are summarized. In the simulation, flows are assumed to be fully turbulent, Spalart- Allmaras turbulence model coupled with N-S equations are solved on parallel computers, flux conservation are enforced at partition boundary. Integrated and distributed aerodynamics loads are compared with experi mental data, lift, drag and pitching moment are shown to be in good agreement, pressure distributions are mostly identical except that on wing tip location, where excessive numerical dissipations are exposed because of wing tip vortex. Three different grids ranging from 466M to 2674M are computed comparatively to study grid convergence at a= 11.02°, the close up to test data are shown through grid refinement, but the curve slope is not a linear, which can be attributed to complexity of flows.