航空機高揚力形態のCFD解析における格子依存剝離の改善

抄録

Grid-induced flow separation which often happens to computational fluid dynamics (CFD) for aircraft high-lift configurations is one of the problems in aircraft aerodynamic design using CFD. This is because the larger uncertainty on the aerodynamic forces due to the grid-dependent results causes the larger design margins on the aerodynamic characteristics, which may cause decreases in the aircraft performance in the certification by analysis. In this paper, grid-induced flow separation on the outboard wing of the NASA high-lift common research model (CRM-HL) is investigated. Steady-state Reynolds averaged Navier-Stokes analysis is conducted on six types of grids at angles of attack 7.05 and 17.05 degrees. The results are analyzed using a grid resolution index which is introduced to evaluate the grid resolution quantitatively. As a result, it is clarified that the grid resolution to capture vortices generated by slat brackets has a relation to the outboard wing flow separation. The results also show that grid refinement using the proposed requirement for the grid resolution index can improve the grid-induced flow separation.