The hydrodynamics and flow structures of a base wing slotted with tip sails in proximity to the ground were studied experimentally in order to investigate the flow control efficiency of wing tip sails in ground effect. The experiment was conducted in a towing tank at a Reynolds number 1.5×10⁵. The lift and drag forces were measured by a transducer, the velocity fields of the wing tip vortices were measured using a time-resolved particle image velocimetry system (TR-PIV). The tip-sails and ground clearance were both effective in reducing the total drag, the lift coefficients of the tip-sails wings were increased as compared with that of a base wing. The lift-drag ratios of the tip-sails wings were improved obviously in a range of angles of attack from 2° to stalling angle. The tip-sails played more important role in unwinding the concentrated wing tip vortices at higher angle of attack, the intensity of the tip vortices were much weaker than that of the base wing. The development of the wing tip vortices was suppressed as well due to the inhibition of the ground, the downwash speed was reduced and the induced drag was decreased.

中文翻译：

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地面效应中翼尖帆的减阻和流动结构

为了研究翼尖帆在地面作用下的流场控制效率，通过实验研究了翼尖帆在地面附近开槽的基翼的流体动力学和流动结构。实验在雷诺数为1.5×10 ⁵的拖曳罐中进行。通过传感器测量升力和阻力，使用时间分辨粒子图像测速系统（TR-PIV）测量翼尖旋涡的速度场。顶帆和离地间隙均有效地减小了总阻力，与基翼相比，顶帆的升力系数有所增加。在从2°到失速角的攻角范围内，前帆翼的升阻比都得到了明显提高。尖端风帆在以较高的迎角展开展开的机翼尖端涡流时起着更重要的作用，尖端涡流的强度比基础机翼弱得多。由于抑制了地面，也抑制了翼尖漩涡的发展，降低了下冲速度，并减少了产生的阻力。