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

地面效应时机翼的升力增大，是由于机翼与地面之间的冲压压力增大。机翼的宽度是有限的，冲压压力逐渐减少到零，在机翼的末端。为了保持较高的冲压压力，我们提出了一种新的系统，该系统在地面上具有表面图案，以防止空气侧向流动。它在地面上有几个纵向的栅栏，在贴近地面飞行的机翼通过流体粘性强烈地受到地面的影响。常规风洞无法估算翼型在洞壁附近的气动特性，因为翼型不相对洞壁运动。因此，有必要使机翼相对于地面运动。We.设计了一种由步进电机精确控制机翼绕圆盘轴旋转的系统。机翼截面为NACA4412，弦长100mm，宽200mm，旋转翼外径1000mm。圆盘的内径为600mm，外径为1000mm，因此在地面上纵向有2mm高的纸张。因此，相邻的距离是1厘米。当机翼后缘高度小于弦长的20%时，升力增大且趋势较强，迎角减小至机翼下表面平行于地面。

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.