多段翼型前缘缝翼位置的优化设计研究

Optimum Design of Multielement Airfoil Slat-Position for Maximum Lift

本文讨论优化前缘缝翼位置的位流设计方法。优化变量为缝翼相对于主翼的缝隙(Gap)、覆盖量(Ouerlap)和偏角δ_s,目标函数为主翼上的压力峰值。应用高阶面元法计算多段翼型压强分布。用Powell优化法使主翼上压力峰值减至最小,以延迟多段翼型的失速,增大最大升力系数。本方法已用于计算NACA64A010两段和四段翼型以及Foster三段翼型,所得结果与实验数据和位流/边界层耦合设计法的结果有很好的一致性。

The paper describes the potential-flow design technique . The primary objective of the theoretical analysis is to determine slat-position of a high-lift devices required to achieve maximum lift. The design variables are the slat gap and overlap (or horizontal and vertical location) and deflection of slat. The objective function is suction peak value on the upper surface of the main airfoil at an angle of attack. The outer potential-flow field and surface pressure distribution on multielement airfoils are calculated by the high order panel method .The analysis is based on the premise that, at the maximum lift coefficient at which attached flow can be maintained on the main airfoil, the optimum slat-position for maximum lift minimizes the suction peak on the upper surface of the main airfoil .The slat gap for these calculation lies close to 0.02c, and the flap gap is more than 0.02c. These gaps are sufficiently large to insure that there is not strong interaction between the wakes and upper surface boundary layers. In this case the potential theory reflects all the primary feature, such as pressure peaks, of the measured pressure distributions. For configurations which stall abruptly this is a reasonable assumption. However, for configuration which stall gradually, the validity of such an assumption remains to be proven.This design technique was used to calculate Foster 3-element airfoil, 2-and 4-element NACA 64A010 airfoils. The results of the calculation are in good agreement with air wind-tunnel testing data and the results of potential-flow/boundary-layer coupling design method.