Image Analysis and Control for Unsteady Structure of Necklace Vortices

项链涡非定常结构的图像分析与控制

• 批准号: 11650196
• 负责人: YAMADA Hidemi
• 金额: $ 2.11万
• 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: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650196/
• 关键词: Necklace Vortex Pattern; Flow visualization; Image Analysis; Boundary Layer Thickness; Circular Cylinder; Rectangular Plate; 三次元流場; 首飾渦構造; 画像処理; 首飾渦; 時空間構造; 可視化; 非定常首飾渦; 動画像解析; 渦制御

The aims of present investigation are to clarify the structure of necklace vortices produced in the junction flow fields around a long cylinder or a rectangular plate mounted on the flat wall, and to know the effects of the Reynolds number and the boundary layer thickness on the necklace vortices structure by means of the flow visualization techniques and the Image analysis method.In the case of the visualization of necklace vortices around the effectively long cylinder, the Reynolds number based on the cylinder diameter was varied in the range between 300 and 2300, and the cylinder was mounted in three different positions from the reading edge of flat plate to vary widely the boundary layer thickness. As the results, the pattern of the necklace vortex system changes keeping laminar flow from one vortex system to three vortex system at the Reynolds number of about 500. Then the necklace vortex pattern changes from three vortex system to five vortex system at the Reynolds number of abou … More t 2000, in this Reynolds number the vortex flow seemed to become unsteady. It will be predicted from the present experiment that the unsteady phenomena was brought from the original vibration of the five necklace vortex system or from the unsteady flow by the transition of laminar boundary layer on the flat wall. In addition, the effect of the necklace vortex on the flow around a circular cylinder was investigated by using the wind tunnel testing. It was known from the results that in the juncture region the necklace vortex made the separation line on the cylinder move back, and made the base pressure behind the cylinder increase and made the drag decrease.In order to clarify the detail of necklace vortices structure, it was tried to increase the relative scale of necklace vortices to the mounted body size. Therefore, the rectangular plate which have various aspect ratios w/h was picked up as the object body instead of a cylinder. The aspect ratio, which was considered to indicates the various shape of the mounted body, of rectangular plate was varied to w/h=0.5, 1, 2, 3, 5 and 7. As the results, it was known that the necklace vortex pattern was strongly dependent on the aspect ratio of plate, but almost independent apart from Reynolds number in this experiment, and the relative scale and the structure of necklace vortices as to the rectangular plate with the same aspect ratio was decided by the ratio of the plate height to the boundary layer thickness. Less

本文的目的是研究平板上长圆柱或矩形平板的连接流场中产生的项链涡的结构，通过流场显示技术和图像分析方法，了解雷诺数和边界层厚度对项链涡结构的影响。有效的长圆柱体，基于圆柱体直径的雷诺数在300和2300之间变化，并且圆柱体被安装在从平板的阅读边缘的三个不同的位置，以广泛地改变边界层厚度。结果表明，在雷诺数约为500时，项链涡系的流型发生了变化，保持层流状态，由单涡系向三涡系转变。当雷诺数约为0.0001时，项链涡的涡型由三涡系变为五涡系。 ...更多信息 t 2000时，在该雷诺数下，涡流似乎变得不稳定。从实验结果可以看出，非定常现象是由五项涡系的初始振动引起的，也可能是由平板壁面层流边界层转捩引起的非定常流动引起的。此外，还通过风洞实验研究了项链涡对圆柱绕流的影响。结果表明，在交界区，项链涡使圆柱分离线后移，圆柱后底压增大，阻力减小，为了更清楚地了解项链涡的结构细节，尝试增大项链涡与安装体尺寸的相对尺度。因此，具有各种纵横比w/h的矩形板被选为对象体而不是圆柱体。矩形板的纵横比（其被认为指示安装体的各种形状）被改变为w/h=0.5、1、2、3、5和7。结果表明，项链涡的涡型与平板的高宽比密切相关，但与雷诺数无关;对于相同高宽比的矩形平板，项链涡的相对尺度和结构由平板高度与边界层厚度的比值决定。少

项目成果

Hidemi YAMADA and Takahiro MAEDA: "Effects of the End Walls on Surface Pressure Distribution of Circular Cylinder"Proceedings of the Japan Society of Mechanical Engineers. No.035-1. 107-108 (2003)

Hidemi YAMADA 和 Takahiro MAEDA：“端壁对圆柱体表面压力分布的影响”日本机械工程师学会会议记录。

山田 英巳, 前田 貴寛: "円柱の表面圧力分布に及ぼす端部側壁の影響"日本機械学会九州支部熊本地方講演会講演論文集. No.035-1. 107-108 (2003)

Hidemi Yamada、Takahiro Maeda：“端部侧壁对气缸表面压力分布的影响”日本机械工程学会九州分会熊本地区会议论文集第 035-108 号（2003 年）。

山田英巳: "十字形配置2円柱の間隙部に生成する首飾渦の可視化"可視化情報. Vol.19,Suppl.No.2. 47-48 (1999)

Hidemi Yamada：“十字形排列的两个圆柱体之间的间隙中产生的项链涡流的可视化”可视化信息，第 19 卷，增刊第 2 号（1999 年）。

山田 英巳, 前田 貴寛: "円柱の表面圧力分布に及ぼすアスペクト比の影響"日本機械学会九州支部熊本地方講演会講演論文集. No.018-2. 151-152 (2001)

Hidemi Yamada、Takahiro Maeda：“长宽比对气缸表面压力分布的影响”日本机械工程学会九州分会熊本地区会议论文集第 151-152 号（2001 年）。

Hidemi YAMADA: "Visualization of Necklace Vortices between Two Cylinders Forming a Cross"Journal of the Visualization Society of Japan. Vol.19, Suppl. No.2. 47-48 (1999)

Hidemi YAMADA：“形成十字形的两个圆柱体之间的项链涡流的可视化”日本可视化学会杂志。