仿生缝翼的增升作用

High-lift effect of bionic slat

以长耳鸮的翅膀为模本构建仿生翼型,并在此基础上构建没有凹口的仿生缝翼及仿生多段翼型。利用快速成型系统制作相应的准二维试验模型,并在低湍流度的风洞内进行试验,结果显示:在攻角小于5°时,仿生翼型的升力系数更大,而在攻角大于5°时,具有仿生缝翼的仿生多段翼型的升力系数更优。同时,仿生多段翼型中仿生缝翼能提高失速角和最大升力系数,而且还能延迟升力系数曲线斜率的下降,从而在一定攻角范围内阻止前缘分离的发生。在低雷诺数下的绕翼烟线显示了仿生翼型的前缘分离,但在相同工况下的仿生多段翼型的流场中没有出现前缘分离。这个优点也许可以被用在未来的前缘缝翼的设计中。

In this paper, a bionic airfoil mimicking the wing of a long-eared owl is proposed. On this basis, a bionic slat without cove and multi-element airfoil is built. In order to reveal high-lift effect of the bionic slat, the corresponding quasi-two-dimensional models are manufactured by rapid manufacturing and prototyping system. Experiments are conducted in a low-turbulence wind tunnel. The results show that the lift coefficient of the bionic airfoil is larger when the angle of attack is less than 5~, but lift coefficient of the bionic multi-element airfoil with slat is larger s when the angle of attack is greater than 5~. The bionic slat can increase the stall angle and the maximum lift coefficient~ at the same time, it can also delay the decline of the lift coefficient curve slope in order to prevent the leading-edge separation within a certain range of angle of attack. Furthermore, the flow field around the models is visualized by smoke wire method, which shows the leading-edge separation of the bionic airfoil at low Reynolds numbers. However, the finding does not occur in the flow field of the bionic multi-element airfoil at the same conditions. This superiority may be used as reference in the design of the leading-edge slat or slot.