正弦派生曲线弯道水流结构特征实验研究

探究窄深型弯曲河段三维水流结构,使用声学多普勒流速仪(ADV)对正弦派生弯道水槽中40个断面12160个测点三维水流数据进行加密测量研究,研究结果表明:弯曲岸壁形态改变了水流结构特征,曲率为0断面附近区域为水流动力轴线在左右两岸摆动的过渡区;在左右两岸侧,纵向流速沿程波动分布,波动周期相同相位相差180°,且在凹岸处存在小流速区;各断面存在中心区近底主环流和近岸近水面反向小环流,部分断面近岸近底还出现与中心环流同向的小环流,环流强度最小值出现在各弯段弯顶附近。实验数据可为连续多个弯道数值模拟提供数据验证参考。

Experimental study on flow structures in sine-generated meandering channel

To study the three-dimensional structure of the flows in a narrow, deep curved main channel in a river reach, we conduct acoustic Doppler velocimetry (ADV) measurements of the 3D flows in a sine-generated meandering laboratory channel, using 12160 gauge points located at 40 cross sections. The results show that in the channel, the curved bank boundaries cause changes in flow structure, and near the cross sections of zero curvature occurs a transition zone where the dynamic axis of flow swings between two banks. In near-bank regions, streamwise velocity takes fluctuating variations along the banks, with low velocity zones occurring near the concave bank; fluctuations along the left and right sides feature the same wave length but a phase difference of 180o. At all the cross sections, a main circulation near the bottom of the channel center and small reverse circulations near the water surface of the near-bank regions can be observed; the main circulation takes the lowest intensity around each bend vertex. At certain cross sections, small circulations rotating in the same direction as the main one also occur near the water surface of the near-bank regions. The experimental data can provide validation for numerical simulation with continuous multiple curves.