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

已经对自由流中引入的湍流边界和纵向涡流阵列之间的相互作用进行了实验研究，以阐明这种相互作用对涡旋结构和边界Layr的影响。 Spanwise的周期性纵向涡流阵列是在自由流中人为生成的。其中一个参数是纵向涡流的跨度周期性l/s（l表示相邻机翼之间的跨度距离，s机翼跨度），规则两种级级，是在湍流边界内引起的次级涡流的流路路径。间歇因子轮廓揭示了对反向二级流的对成对的影响，这表明了机翼的中跨的倾斜流，相反，相邻机翼的中心切片的上流流量。间歇性因素受到邻近机翼之间的间距的强烈影响。间歇性因子的值降低了……更多的内层，随着机翼的中跨度的增加，L/s增加了。涡旋矢量纵向成分的估计带来了有关纵向涡流特征（如路径和强度）的新信息。对涡旋矢量的其他两个剩余的成分的进一步分析证实，在L/S <1的情况下，涡流相互作用，导致涡旋强度突然丧失，但与边界的相互作用非常弱。另一方面，在L/S*1的情况下，发生涡流轴发生变化。考虑的下一个阶段是在控制体积上集成的涡度传输方程，以找到涡度通量。选择了控制量，以便在任何流式位置都只能在内部找到一个涡流。较小的跨度周期导致涡度通量的较高变化。另一方面，较大的跨度周期会导致稳定下降的涡度通量，除了涡旋轴在篮板上发生变化所产生的微小变化。较少的