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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

本文通过实验研究了湍流边界层与自由流动中引入的纵向涡阵列之间的相互作用，分别阐明了这种相互作用对涡旋和边界层结构的影响。在自由流中人工产生了沿展向周期性纵向涡阵。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表示翼型跨度），决定了湍流边界层内产生的二次涡的大小和流向。间歇因子剖面揭示了对反旋转二次流的影响，对翼型跨中部表现为下洗流，而对邻近翼型中心片则表现为上洗流。间断性因素受到邻近翼型间距的强烈影响。在翼型中跨处，随着L/S的增大，间隙系数的值逐渐减小。对涡度矢量纵向分量的估计，提供了纵向涡路径和强度等特征的新信息。进一步分析涡度矢量的其他两个分量，证实了在L/S<1的情况下，涡旋之间的相互作用导致涡旋强度的突然丧失，但与边界的相互作用非常弱。另一方面，在L/S*1的情况下，发生涡轴变化。下一阶段考虑的是在控制体积上积分涡度输运方程，以求涡度通量。控制体积的选择，使在任何流向的位置，只有一个漩涡应该被发现在里面。小的展向周期导致涡度通量的大变化。另一方面，大的展向周期导致涡量通量稳步下降，除了在反弹点涡轴变化的影响产生的轻微变化。少