【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。更多还原

【Abstract】 This study investigated the flow structures in the near-field of an emerged spur dike under different hydraulic gradients by laboratory experiments using ultrasonic wave and PIV technical methods for measuring the water level and velocity, respectively. Experimental results showed that with the decrease in the hydraulic gradient,at the head of the dike, the area of the strong turbulence intensity gradually spread toward the main stream and upstream. At the downstream of the dike, the lowest point of the hydraulic gradient dropped gradually downward, and the vortex center was close to the wall of the dike side. There was no obvious relationship between the change in the length and width of the recirculation zone and the change in the hydraulic gradient; however, a highly linear relationship was observed between the velocity in the region near the dike head and the length and width of the recirculation zone. These research achievements reveal the mechanism of the regulative action of the dike to the flow structure under different hydraulic gradients. At the same time, these findings could clearly explain the difference in the length of the recirculation zone obtained by measurements of previous researchers and further provide a scientific basis for designing the spur dike and planning the river shoreline.更多还原