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

在地面效应下，由于翼型与地面之间的冲击压力增强，翼型的升力增大。由于机翼的宽度受到限制，在机翼末端冲压压力逐渐减小至零。为了使闸板压力保持在较高的水平，我们提出了新的系统，它在地面上有表面图案，防止空气向侧面流动。它在地面上有几个纵向的栅栏。靠近地面飞行的翼型通过流体粘度受到地面的强烈影响。由于翼型在风洞壁上不相对运动，传统的风洞无法估计翼型在风洞壁上的气动特性。因此，有必要运行相对于地面的翼型。我们。设计了一种机翼绕圆盘轴线旋转的系统，圆盘高度由步进电机精确控制。机翼截面为NACA4412，弦长100mm，宽200mm，旋转翼外径1000mm。圆盘内径600mm，外径1000mm。地面上的纵向因此有2mm高的纸张。相邻点之间的距离是1cm。当机翼尾缘高度小于20%弦长时，升力增大且趋势较强，攻角减小至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.