椭圆平板MAV低雷诺数气动特性数值模拟研究

The CFD Research on Low-Reynolds-Number Aerodynamic Performance of Elliptical Flat-Plate MAV

采用Realizable k-ε湍流模型,通过基于压力的算法求解定常不可压三维N-S方程,研究不同展弦比、上反角椭圆形平板MAV在低雷诺数下的流场及气动特性。结果显示,翼尖涡和前缘涡是低雷诺数小展弦比椭圆平板MAV外流场的主要组成;上反角会改变流场中涡的相对位置,影响翼表面压力的分布。分析表明,气动特性会随着展弦比(AR≤1.5)的增加而提高,较小的上反角对升阻特性略有改善,并能提高大迎角下,MAV的纵向静稳定性。

The steady incompressible tri-dimensional Navier-Stokes equations are solved under the realizable k-ε turbulent model with a pressure-based algorithm. A series of numerical calculations are conducted for low-Reynolds-number aerodynamic performance of elliptical flat-plate MAVs(micro aerial vehicle) with different small aspect ratios and dihedral angles. Showthat both wing-tip vortex and leading-edge vortex are key flowcomponents of elliptical flat-plate MAV,dihedral angles could change the relative position of vortexes in the flowas well as the pressure distribution beyond the wing surface. It is found that the MAVs will showbetter aerodynamic performance with the increase of aspect ratio(below1. 5). Relatively small dihedral angles could improve the lift-drag ratio and enhance longitudinal static stability under large angle of attack.