单发螺旋桨飞机滑流影响试验

Experiment of the effect of propeller slipstream on single-engine airplanes

螺旋桨滑流会使飞机翼面的有效迎角和气流速度发生变化,影响全机气动特性。单发螺旋桨飞机螺旋桨与机翼的相对位置关系相比机翼螺旋桨飞机灵活多变,为了研究不同气动布局单发螺旋桨飞机滑流对机翼的影响,本文针对上单翼和下单翼轻型单发螺旋桨飞机构型的滑流影响进行了测力风洞试验研究。试验发现:受滑流影响,对试验模型的机头进气口进行简单的封堵会产生较大的附加阻力,该附加阻力随螺旋桨拉力系数增大而增大,其量值基本不受襟翼偏度影响;螺旋桨滑流使得单发螺旋桨飞机升力曲线斜率增加,最大升力系数提高,阻力增大,全机升阻比降低,抬头力矩增加,全机纵向稳定性略微降低。机头螺旋桨与机翼的相对位置关系对全机失速迎角有着较大的影响,滑流影响使得上单翼单发螺旋桨飞机失速迎角推迟,使得下单翼单发螺旋桨飞机失速迎角提前。进一步的流场显示试验及理论分析表明,滑流移动到下单翼单发螺旋桨飞机机翼上方引起强烈的上洗流动,增大了机翼当地迎角,从而导致机翼上表面出现大面积流动分离区,飞机失速迎角提前。

The propeller slipstream will change the effective angle of attack and air velocity of the airplane wing,affecting the aerodynamic characteristics of the whole airplane.Compared with wing-mounted propeller airplane,the relative position relationship between propeller and wing of single-engine propeller airplane is flexible and changeable.In order to study the influence of slipstream of single-engine propeller airplane with different aerodynamic layouts on the wing,this paper studies the influence of slipstream on light single-engine low-and high-wing propeller airplanes by force-measuring wind tunnel tests.The results verify that the simple plugging of the nose air inlet of the test model will produce considerable additional drag due to the propeller slipstream;the additional drag is proportional to the propeller thrust coefficient but independent of the flap deflection.Propeller slipstream increases the lift curve slope,maximum lift,drag and pitching moment,but somewhat reduces the lift-to-drag ratio and longitudinal stability.The relative position between the nose propeller and the wing significantly affects the stall angle of attack.Propeller slipstream increases the stall angle of attack for single-engine high-wing airplanes but decreases that for single-engine low-wing airplanes.The flow visualization and theoretical analyses show that the propeller slipstream moves to the top of the wing of single-engine low-wing airplanes,causing strong upwash flow,increasing the local angle of attack of the wing,resulting in a large flow separation region on the upper surface of the wing,and reducing the airplane stall angle of attack.