剪切翼梢增升减阻机理

MECHANISM OF LIFT AUGMENTATION AND DRAG REDUCTION ON THE SHEARED WING-TIP

在计算与风洞实验的基础上 ,提出了机翼剪切翼梢气动布局 ,对平面形状与翼型进行了优化设计 ,达到了巡航状态与爬升阶段较高的增升减阻要求。计算采用涡格面元法与涡升力展向分布吸力比拟法相结合的方法 ,既能考虑气动力的非线性因素 ,又有较高的计算精度与速度。计算结果与实验数据十分吻合。通过分析得到 ,在矩形翼翼梢处增加具有较大前缘后掠角的梯形剪切翼梢有不仅增加机翼展弦比 ,且可改变展向环量分布 ,使其接近椭圆分布 ;剪切翼梢上的前缘涡可抑制翼端涡的作用 (使翼端涡强度变弱 ) 。

Based on computation and wind tunnel test, a rational aerodynamic configuration of sheared wing tip is posed, including optimum design of planform and airfoil, and the higher demands of increased lift and reduced drag at cruise and in climb are met. A method combining both the panel vortex lattice method and the suction analogy method of the vortex lift distribution in the span direction is adopted,which may account for the nonlinear aerodynamics and raise the calculation precision and speed. The computation and experimental data are in fair agreement. After analyses, it is obtained that a sheared wing tip with highly leading edge swept angle, mounted on the tip of a rectangular wing, can make the spanwise circulation distribution of the wing close to an elliptical distribution,and the leading edge separated vortex on the sheared wing tip may restrain the trailing vortex on the wing tip (to cause the trailing vortex strength to drop),and may produce additional lift on the sheared wing tip.