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Management of the Turbulent Boundary Layer using the Strong Spanwise Deformation by a Pair of Streamwise Vortex

利用一对流向涡强展向变形管理湍流边界层

基本信息

批准号：
09650191
负责人：
OSAKA Hideo
金额：
$ 1.79万
依托单位：
YAMAGUCHI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650191/
关键词：
Turbulent Boundary Layer A Pair of Streamwise Vortex Management (Control)Secondary Flow Spanwise Rate of Strain Interaction Process 干渉

项目摘要

The interaction process between a turbulent boundary layer and a pair of vortex introduced in the main flow has been examined experimentally. Both longitudinal vortex pair with "common-flow" down and "common-flow" up, were generated by a deltawing set * 8ﾟ angle-of-attack. The generator height was selected to provide a vortex which would be obtained the experimental parameters, such as GAMMA/U_1 delta_0 <1, GAMMA / utau delta_0 * 1 and d_0 / delta_0* 1( GAMMA : vortex circulation, U_1 : free stream velocity, delta_0 : initial boundary layer thickness, Utau : friction velocity, d_0 : vortex diameter). Isovels of mean vorticity and secondary flow vectors revealed a pair of streamwise vortex of which center located at the position inside 30% of wing span for both cases "common-flow" down and up. In case of common-flow up, streamwise vortex reduce faster after the investigation on vortex path and vorticity decay, and the effect of streamwise vortex on the boundary layer characteristics is limited to the spanwise local region. In both cases of common-flow up and down, however, mean velocity, turbulent intensity and Reynolds shear stress values are significantly altered near the location of vortex center. Each isovels of turbulent quantities are deformed at some slice between neighboring vortex due to the effect of the extra rate of strain. Wall shear stress at the spanwise center position' shows peak value in case of common-flow down, conversely minimum one in case of common-flow up due to the secondary flow effect. A discontinuity on three-dimensional separation line is not formed anywhere in spanwise slice. Local similarity evaluated with local scales does not establish in the inner layer in both cases of common-flow down and up. The effect of Reynolds normal stress difference on the streamwise vortex remaining is significantly large. In the next stage, turbulence management using a pair of streamwise vortex must be considered.

本文通过实验研究了湍流边界层与主流中引入的一对涡之间的相互作用过程。纵向涡对均为“共流”向下和“共流”向上，由一组* 8的攻角delta集产生。选取发生器高度提供涡，得到GAMMA/U_1 delta_0 <1、GAMMA/ utau delta_0* 1和d_0 / delta_0* 1实验参数（GAMMA：涡环流，U_1：自由流速度，delta_0：初始边界层厚度，utau：摩擦速度，d_0：涡直径）。平均涡量和二次流矢量等水平显示，在“共流”上下两种情况下，均存在一对流向涡，其中心位于翼展30%以内的位置。在共流向上的情况下，通过对涡路和涡度衰减的研究可知，流向涡减小得更快，并且流向涡对边界层特性的影响仅限于展向局部区域。而在共流向上和向下两种情况下，平均速度、湍流强度和雷诺剪应力值在涡中心附近都发生了显著变化。由于额外应变速率的影响，湍流量的每个等水平线在相邻涡之间的某个切片上发生变形。沿展向中心位置的壁面剪应力在共流向下时最大，在共流向上时由于二次流的作用最小。在展向切片的任何地方都不会形成三维分离线上的不连续。在共流上下两种情况下，用局部尺度评价的局部相似度在内层均不成立。雷诺数法向应力差对沿流涡剩余量的影响非常大。在下一阶段，必须考虑使用一对流向涡来进行湍流管理。