Tree-dimensional Measurement of Thrbulence Structure in Open Channel Flows by Flow Visualization and Picture Processing

通过流可视化和图像处理对明渠流湍流结构进行树维测量

• 批准号: 08555131
• 负责人: UENO Tetsuo
• 金额: $ 1.6万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08555131/
• 关键词: Open Channel Flow; Unsteady Flow; Compound Channel; Turbulence; Flow Visualization; Picture Processing; 動画像解析; 開水路流れ; 乱流; 三次元計測法; 開水路流; 水理実験; 複断面蛇行流

First, the large scale structure of turbulence in an open channel flow was examined by flow visualization and picture analysis. A horizontal cross-section of the flow was illuminated by a sheet of light and a pair of photographs ware taken in a short span of time using the 35 mm movie camera. Then the illuminated cross-section was quickly shifted upward and another pair of pictures ware taken. 15 pairs of photographs ware taken from the channel bed to the water surface during about 1 second. The photographs ware digitized by a CCD digital camera and velocity vectors ware calculated by multi-step correlation technique. Characteristic features of turbulence structures near the channel bed and in the upper layer ware elucidated based on the three-dimensional distribution of the velocity and the vorticity.Secondly, the turbulence structures of the unsteady smooth open channel flow were examined by flow visualization and image processing. Based on the data obtained by the image processing, the characteristic features of the horseshoe vortex and parallel spiral flows with longitudinal axes ware elucidated.Thirdly, the flow patterns in three types of meandering channels with compound cross-section were examined by flow visualization and image processing. Based on the data obtained by the image processing, the characteristic features of the large scale turbulence structures in the best type of meandering channels with compound cross-section ware elucidated.

首先，利用流动可视化和图像分析技术研究了明渠湍流的大尺度结构。用一束光照射流的水平横截面，并用35毫米胶片相机在短时间内拍摄了一对照片。然后，被照亮的横截面迅速向上移动，拍摄另一对照片。在大约1秒的时间内，从河床到水面共拍摄了15对照片。利用CCD数码相机对图像进行数字化处理，利用多步相关技术计算速度矢量。根据流速和涡度的三维分布，阐明了河床附近和上层湍流结构的特征特征。其次，采用流动可视化和图像处理技术对非定常光滑明渠流动的湍流结构进行了研究。根据图像处理得到的数据，阐明了马蹄涡和纵轴平行螺旋流的特征。第三，采用流动可视化和图像处理技术对三种复合断面曲流通道的流动形态进行了研究。在图像处理数据的基础上，阐明了最佳复合截面曲流通道中大尺度湍流结构的特征。