菱形翼布局太阳能无人机螺旋桨滑流影响研究

In order to investigate the influence of propeller slipstream on the aerodynamic characteristics of low Reynolds number diamond joined-wing configuration solar-powered UAV with different rotational speeds. It was simulated accurately by solving the Reynolds Averaged Navier-Stokes (RANS) equation based on Momentum Source Method (MSM) and k-k_L-ω transition model. The mechanism of the propeller slipstream effects at different angles of attack and rotational speeds was analyzed by comparing the flow field structure and pressure distribution on the wing surface. The research shows that with the increase of the propeller rotational speed at low angle of attack, the propeller slipstream leads to the obvious increment of lift and decrement of drag. And the maximum lift-to-drag ratio is increased by 18.4% at 3 000 r/min. At low angle of attack, the air flow is accelerated by propeller, and it leads to increment of lift for the Frt-wing. And for the Aft-wing, the rotation of the air flow leads to decrement of pressure drag because of the emergence of low-pressure region at lower surface of leading edge. At high angle of attack, the effects of propeller to the Frt-wing are not changed. However for Aft-wing, the range and strength of low-pressure region at lower surface of leading edge decrease, which leads to the disappearance of negative lift area at leading edge as well as the notable increase of the lift and the pressure drag. Besides, since the main contribution components of lift increment are different at different angles of attack, the longitudinal static stability margin of UAV shows an enhancement with the increase of propeller rotational speed. The diamond joined-wing configuration solar-powered UAV can effectively utilize the slipstream of propeller to improve the aerodynamic performance by reasonably setting the position and speed of propeller.