摘要: |
采用超声水位和PIV流速测量技术,对不同水力坡度下非淹没丁坝近区的水流结构进行了试验研究。结果表明,随着水力坡度的降低,在坝头处,紊动强度较大的区域逐渐向主流区及上游扩散;在坝后,跌水最低点逐渐下移,漩涡中心向丁坝侧边壁靠近。回流区长度与宽度的变化和水力坡度的变化无明显对应关系,但坝头近壁区的流速与坝后回流区的长度及宽度存在高度响应的线性关系。研究成果揭示了丁坝在不同水力坡度下调整水流结构的机理,同时对各家测量得到的回流区长度不等有了较明确的答案,为工程中丁坝的设计及河道岸线的规划提供了科学依据。 |
关键词: 水力坡度 非淹没丁坝 紊动强度 回流区 坝头近壁区的流速 |
DOI:10.11759/hykx20180328002 |
分类号:TV863 |
基金项目:国家自然科学基金项目(41776098) |
|
Influences of different hydraulic gradients on flow structures near the spur dike |
GU Jie1, ZHENG Jian1, ZHENG Yu-hua2, KUANG Cui-ping2
|
1.College of Marine Ecology and Environment,Shanghai Ocean University;2.College of Civil Engineering,Tongji University
|
Abstract: |
Using ultrasonic wave and PIV technical methods for measuring water level and velocity respectively, the flow structures in the near-field of an emerged spur dike are studied under different hydraulic gradients by laboratory experiments. Experimental results show that with the decrease of hydraulic gradient, at the head of the dike, the area of strong turbulence intensity gradually spreads toward the main stream and upstream; at the downstream of the dike, the lowest point of hydraulic drop gradually downward, the vortex center is close to the wall of the dike side. There is no obvious relationship between the change of the length and width of recirculation zone and the change of hydraulic gradient, however, there is a highly linear relationship between the velocity in the region near the dike head and the length and width of the recirculation zone. The research achievements reveal the mechanism of the regulative action of the dike to the flow structure under different hydraulic gradient. At the same time, they can give a clear answer to the difference of the length of recirculation zone obtained by previous researchers’ measurements and provide scientific basis for the design of spur dike and the planning of river shoreline. |
Key words: hydraulic gradient, emerged spur dike, turbulent energy, recirculation zone, velocity in the region near the dike head |