关键词: 数值模拟, 阻力系数, 重叠网格, 多层多块嵌套策略, 隐式切割方法, 翼身平尾组合体

Abstract:

A multi-layer multi-block overset grid technique is presented to accurately simulate the viscous flows around the wing-body-tail (WBT) configuration of a common NASA research model (CRM). Based on the hierarchical overset grid strategy and the implicit hole cutting algorithm, this technique selects the "best" cells located in the overlapped regions by the criterion of cell size, rather than bydetermining whether a computed cell is lying inside (hole cell) or outside (not a hole cell) of a specified region. Four types of grids are built for a CRM WBT configuration proposed in the fourth drag prediction workshop (DPW-4), and viscous flows around the configuration are analyzed by an in-house computational fluid dynamic (CFD) solver. The numerical results show that all the aerodynamic forces matched well with those of CFL3D and OVERFLOW, which demonstrates the accuracy and efficiency of the in-house CFD solver. When the angle of attack is larger than 3°, separation bubbles at the wing and tail trailing edge have some influence on the aerodynamic performance of the CRM WBT configuration. The overset grid density is used to study drag prediction, and computational drag is more accurate with larger sizes of grids. Because the two turbulence models present different predictions of the effect of lift-drag performance, selection of turbulence models is also worth considering on drag prediction.

Key words: numerical simulation, drag coefficient, overset grids, hierarchical grid system, implicit hole cutting, wing-body-tail configuration