Research on Airfoil Stall Suppression Control by Use of a Smart-structure Device

在层流边界层从翼型表面分离后，流动可以作为湍流剪切层重新附着到表面。层流分离和再附着之间的这个区域称为层流分离泡。当翼型失速时，层流分离泡破裂发生。翼型的失速特性强烈地依赖于层流分离泡。另外，在失速附近的层流分离泡内部还观察到低频振荡。本研究的目的是研究层流分离泡破裂，并建立一种抑制翼型失速的方法。为此，进行了以下研究项目，首先扩展关于层流分离泡的非定常流动行为的知识，其次确认破裂抑制装置对翼型的影响，最后，利用智能结构控制装置对翼型绕流进行控制，从而控制翼型失速。结果表明，失速附近层流分离泡的非定常特性; 2）在翼型上成功地应用了防突爆控制板来控制翼型失速; 3）采用智能结构装置来抑制失速。4）研究了不同截面形状的弧形平板机翼上层流分离泡的特性。

After the laminar boundary layer separates from the airfoil surface, the flow can reattach to the surface as a turbulent shear layer. This region between the laminar separation and the reattachment is called a laminar separation bubble. When the airfoil stalls, the laminar separation bubble burst occurs. The stall characteristics of the airfoil are strongly dependent upon the laminar separation bubble. It is also known that a low frequency oscillation is observed inside the laminar separation bubble near stallThe purpose of this research is to investigate the laminar separation bubble burst and to construct a method to suppress the airfoil stall. For this purpose, the following research items were investigated, firstly to extend the knowledge on an unsteady flow behavior of the laminar separation bubble, secondly to confirm the effect of burst suppression device on the airfoil, and finally to control the flow around the airfoil by use of a smart-structure device to control the airfoil stallThe conclusions of the present research are as follows.1) It was revealed the unsteady nature of the laminar separation bubble near stall.2) Burst suppression control plate was successfully applied for the airfoil to control the airfoil stall.3) Smart-structure device was also applied for the stall suppression. Some benefit was observed by use of this device.4) The behavior of the laminar separation bubble formed on a cambered plate wing, that has a different cross section compared with an ordinary airfoil, was also investigated.