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Structure Analysis and Control of Necklace Vortices Generated between Two Circular Cylinders Forming a Separating Cross

形成分离十字的两个圆柱体之间产生的项链涡流的结构分析与控制

基本信息

批准号：
14550168
负责人：
YAMADA Hidemi
金额：
$ 1.79万
依托单位：
Tokuyama College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The three dimensional flow field area and the necklace vortices structure around two cylinders forming a separating cross were visualized using a dye injection method and a tracer particle method under the Reynolds number between 500 and 2000, and the surface pressure distribution on two circular cylinders was measured under the Reynolds number between 1000 and 8000 in detail to clarify the necklace vortex structures in uniform flow and the effects of the necklace vortex behavior on the fluid force into and on the separation flow from the cylinders. In addition, the relationship between the necklace vortex structure being made change by the gap distance and the pressure distribution on the surface of the cylinders was investigated.It is found that the various patterns of the necklace vortices system are produced, depending on the gap distance "G" between two cylinders. In the case of the gap distance ratio "G/d" between 0 and 0.1, the boundary layer on the surface of the upstream cylinder separates and rolls up as a small necklace vortex in the front of the downstream cylinder, and the vortex system with 4 vortices is produced in the symmetrical plane of y/d=0. In the case of G/d=0.2-1.0, a pair of main necklace vortices grows in the gap space between two cylinders, and the 8 vortices system as total is produced. In the case of G/d=1.0-1.5, the pair of main necklace vortices starts vibrating as well as twin vortices behind a cylinder in the low Reynolds number. In the case of G/d=1.5-2.0, the behavior of necklace vortices behind the upstream cylinder is similar to that of Karman vortices under the low Reynolds number.

采用染料喷射法和示踪粒子法，在雷诺数为500 ~ 2000的范围内，对形成分离十字的两圆柱绕流的三维流场区域和项链涡结构进行了可视化，并详细测量了雷诺数在1000 ~ 8000之间的两个圆柱表面压力分布，以阐明项链涡结构。均匀流和项链涡行为对进入圆柱体的流体力和对来自圆柱体的分离流的影响。此外，还研究了差距距离改变项链涡结构与圆柱表面压力分布的关系，发现随着差距距离G的增大，项链涡系统的形态也会发生变化。在差距距离比“G/d”介于0 ~ 0. 1的情况下，上游圆柱表面的附面层在下游圆柱前部分离并卷起为小项链涡，在y/d=0的对称平面内产生4个涡的涡系。在G/d=0.2-1.0的情况下，两圆柱间的差距空间中产生一对主项链涡，共产生8个涡系。在G/d=1.0-1.5的情况下，在低雷诺数下，柱后主项链涡对和双涡开始振动。在G/d=1.5-2.0的情况下，上游圆柱后面的项链涡的行为与低雷诺数下的卡门涡的行为相似。