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Vortex structure model in the turbulent boundary layr interacted with longitudinal vortex arrays (1996)

与纵向涡阵列相互作用的湍流边界层中的涡结构模型（1996）

基本信息

批准号：
07650208
负责人：
OSAKA Hideo
金额：
$ 1.41万
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：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

The interaction between a turbulent boundary layr and longitudinal vortex arrays introduced in the free stream has been investigated experimentally in order to clarify the effect of this interaction on the structure of the vortices and the boundary layr, respectivly. The spanwise periodic longitudinal vortex arrays are artificially generated in a free stream. One of the parameters, spanwise periodicity of longitudinal vortices L/S (L denotes the spanwise distance between neighboring airfoils, S the airfoil span), rules both magnitude an streamwise path of secondary vortices caused within the turbulent boundary layr. Intermittency factor profiles revealed the effect of pairs of counterrotating secondary flows which showed the downwash flow for the midspan of the airfoil, and conversely, the upwash flow for the center slice of neighboring airfoils. Intermittency factors are strongly affected by the spacing between neighboring airfoils. The value of the intermittency factor decreases in t … More he inner layr with increasing L/S at the midspan of the airfoil. The estimation of the longitudinal component of vorticity vector brings new information about the longitudinal vortex characteristics, like path and strength. A further analysis of the other two remaining components of vorticity vector confirm the fact that, in the case of L/S<1, the vortices interact with each other leading to an abrupt loss of vortex strength but the interaction with the boundary is very weak. On the other hand, in the case of L/S*1, the vortex axis changing occurs. The next stage considered was the vorticity transport equation integrated over a control volume in order to find the vorticity flux. The control volume has been chosen so that at any streamwise location only one vortex should be found inside. The small spanwise period leads to high variations of the vorticity flux. The large spanwise period, on the other hand, leads to a steadily decreasing vorticity flux except for a slight variation that is produced by the effect of the vortices axis changing at the rebounding points. Less

本文对自由流中纵向涡列与湍流边界层的相互作用进行了实验研究，以阐明这种相互作用对涡结构和边界层结构的影响。在自由来流中人工生成展向周期性纵向涡列。其中一个参数，纵向涡的展向周期性L/S（L表示相邻翼型之间的展向距离，S表示翼型翼展），决定了湍流边界层内产生的二次涡的大小和流向路径。间歇性因子剖面显示了反向旋转二次流对的影响，显示了翼型翼展中部的下洗流，相反，显示了相邻翼型中心片的上洗流。相邻翼型之间的间距强烈影响间歇因子。在t中，不透明度因子的值减小 ...更多信息在翼型的中翼展处，随着L/S的增加，内层的厚度增加。涡度矢量经向分量的估算为纵向涡的运动路径和强度等特征提供了新的信息。对涡量矢量其余两个分量的进一步分析表明，在L/S<1的情况下，涡之间相互作用，涡强度突然减弱，但与边界的相互作用很弱。另一方面，在L/S*1的情况下，涡轴发生变化。下一阶段考虑的是涡量输运方程集成在一个控制体积，以找到涡量通量。控制体积的选择使得在任何流向位置，内部只能发现一个涡流。小的展向周期导致涡度通量的高变化。另一方面，大的展向周期导致涡量通量稳定地减小，除了由涡轴在回弹点处改变的影响产生的微小变化之外。少