Effect of Ground Surface Patterns on Aeroflie Lift in the close proximity to the Ground

由于翼型与地面之间的冲压增强，机翼在地面效应中的升力增大。机翼的宽度是有限的，机翼末端的冲头压力逐渐降低到零。为了使柱塞压力保持在较高的水平，我们提出了在地面上设置表面图案的新系统，以防止空气侧向流动。它在地面上有几个纵向的栅栏。在靠近地面飞行的机翼，通过流体的粘性受到地面的强烈影响。由于翼型不是相对于壁面运动，常规风洞不能估算翼型在风洞壁面附近的气动特性。因此，机翼相对于地面运行是必要的。我们。设计了一种机翼绕圆盘轴线旋转的系统，通过步进电机精确控制圆盘的高度。机翼截面为NACA4412，弦长100 mm，宽度200 mm，旋转翼外径1000 mm。圆盘的内径为600 mm，外径为1000 mm，因此在地面上纵向上有2 mm高的纸。因此，邻居之间的距离为1厘米。当机翼尾缘高度小于弦长的20%时，升力增大且趋势较强，攻角减小到机翼下表面与地面平行。

The lift of aerofoil in the ground effect increases, because the ram pressure between the aerofoil and the ground is strengthen. The width of the wing is limited, the ram pressure decreases gradually to zero at the end of the wing. To keep the ram pressure at high level, we proposed the new system which has surface pattern on the ground, which prevents the air to flow the sideways. It has several longitudinal fences on the ground surface.The aerofoil flying in the close proximity to the ground is strongly affected by the ground through fluid viscosity. The conventional wind tunnel can not estimate the aerodynamic characteristics of the aerofoil near the wind tunnel wall, because the aerofoil does not run relative to the wall. So, it is necessary to run the aerofoil relative to the ground. We. designed a system in which the wing rotates about the axis of the circular disk whose height is precisely controlled by the stepping motor. The wing section is NACA4412, chord length 100mm, width 200mm, the outer diameter of the rotating wing is 1000mm. Inner diameter of the circular disk is 600mm and outer diameter is 1000mm.The longitudinal hence on the ground has 2mm height of papers. The distance between neighboring hence is 1cm. When the height of the wing trailing edge is less the 20% of the chord length, the lift force increase and the tendency is strong, the attack angle decrease to the lower surface of the wing is parallel to the ground.