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.

本研究研究了具有非对称空腔的明渠流动。该流动也可以被认为是具有不同纵横比的空腔的后步流动。在所研究的流动情况中，流动在腔体入口处显示出临界深度，并且在腔体下游产生水力跳跃。根据初步目视调查，随着空腔纵横比的增加，水跃向上游向空腔移动。当水跃的位置变得非常接近空腔时，水跃突然开始振荡。这种现象可以认为是分离涡与水面相互作用的结果。为了理解这些流动特征的机制，引入图像分析技术来测量周围纵向垂直横截面的二维速度场。空腔区域。使用高速摄像机和高分辨率摄像机来捕获通过激光光片可视化的示踪粒子的连续流图像。二维速度矢量可以通过使用粒子图像测速技术（例如 PIV 或 PTV）来获得。在本研究中，PTV 用于稳定流，PIV 用于非稳定振荡水跃。很明显，当空腔长度大于入口流的重新附着长度时，能量耗散变大。此外，在振荡水跃情况下，通过速度演变图清楚地表明了随时间变化的流动特性。

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.

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。

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.

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

Fujita, I. 和 Tohmatsu, A.：“PTV 测量三维明渠流量”第三届 PIV 99 圣巴巴拉国际研讨会论文集。