Interaction between open-channel turbulence and separation bubble in a cavity under a flow with a large water surface deformation

大水面变形流下明渠湍流与腔内分离气泡的相互作用

• 批准号: 10650502
• 负责人: FUJITA Ichiro
• 金额: $ 1.15万
• 依托单位: Kobe University (1999)Gifu University (1998)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650502/
• 关键词: open-channel turbulence; separation vortex; cavity flow; hydraulic Jump; image analysis; flow visualization; particle image velocimetry; 乱流計測; 画像解析; トレンチ; 水面変動場

Open-channel flow with a non-symmetric cavity was investigated in this research. The flow can also be considered as a back-step flow with a cavity of various aspect rations. In the flow situation investigated, the flow shows a critical depth at the inlet of the cavity and a hydraulic jump is created downstream of the cavity. According to the preliminary visual investigation, the hydraulic jump shifts upstream towards the cavity as the aspect ratio of the cavity increases. When the location of the hydraulic jump becomes very close to the cavity, the hydraulic jump suddenly begins to oscillate. This phenomenon can be considered as a result of the interaction between separation vortices and water surface.In order to understand the mechanism of these flow features, image analysis techniques were introduced for measurements of two-dimensional velocity fields in a longitudinal vertical cross-section around a cavity area. A high-speed video camera and a high-resolution video camera were used to capture consecutive flow images of tracer particles visualized by a laser light sheet. Two-dimensional velocity vectors can be obtained by using particle image velocimetry techniques such as PIV or PTV. In this research, PTV was used for a steady flow and PIV for unsteady oscillating hydraulic jump. It was made clear that the energy dissipation becomes large when the length of the cavity is greater than the reattachment length of the inlet flow. In addition, the time-dependent flow characteristics were made clear by a velocity evolution diagram in the case of an oscillating hydraulic jump.

本文研究了具有非对称空腔的明渠水流。该流动也可以被认为是具有各种长宽比的空腔的后台阶流动。在研究的流动情况下，流动在空腔的入口处显示出临界深度，并且在空腔的下游处产生水跃。根据初步的视觉调查，水跃移上游的空腔的长宽比增加。当水跃的位置变得非常接近空腔时，水跃突然开始振荡。为了了解这些流动特征的形成机理，采用图像分析技术对空泡区纵向垂直截面上的二维速度场进行了测量。使用高速摄像机和高分辨率摄像机捕获通过激光光片可视化的示踪颗粒的连续流动图像。二维速度矢量可以通过使用粒子图像测速技术如PIV或PTV获得。在这项研究中，PTV用于稳定的流动和非定常振荡水跃的PIV。结果表明，当空腔长度大于来流的再附着长度时，能量耗散变大。此外，还绘制了振荡水跃情况下的流速演化图，揭示了水流的时变特性。

项目成果

Fujita,I. and Maruyama,T.: "Energy dissipation at non-symmetric trench flow (in Japanese)"JSCE Kansai Chapter, Proc of Civil Engineers. (to be published). (2000)

藤田，I.

Muste,M., Xiong,A., Kruger,A. and Fujita,I.: "Error estimation applied to large-scale flows"Proc. of the 3rd Int. Workshop on PIV'99 -Santa Barbara. 573-578 (1999)

穆斯特，M.，熊，A.，克鲁格，A.

Fujita,I. and Tohmatsu,A.: "Measurement of three-dimensional open-channel flow by PTV"Proc. of the 3rd Int. Workshop on PIV'99 -Santa Barbara. 619-624 (1999)

藤田，I.

Maste,M.,Xiong,A,Kruger,A.and Fujita,I.: Proceedings of the Third International Workshop on PIV'99-Santa Barbara. 573-578 (1999)

Maste,M.、Xiong,A、Kruger,A. 和 Fujita,I.：第三届 PIV99 圣巴巴拉国际研讨会论文集。

藤田一郎、丸山達弥: "非対称トレンチ流れにおけるエネルギー損失"平成12年度関西年次学術講演概要. (印刷中). (2000)

Ichiro Fujita、Tatsuya Maruyama：“非对称沟渠流中的能量损失”2000 年关西年度学术讲座摘要（2000 年）。