黄河什四份子弯道冰下环流特性研究

Experimental study on characteristics of subglacial circulation for Shisifenzi bend flow in Yellow River

为分析弯道冰下水流结构与环流分布特征,利用声学多普勒流速剖面仪(ADCP)对什四份子弯道的冰下流场进行了测量,通过测量弯道的冰厚、水深、流速,分析了弯道断面冰情与冰下环流分布情况。结果表明:弯道冰下水流并不完全呈现双螺旋结构,冰封期环流集中在弯顶凹岸侧和弯顶后凸岸侧,易产生在相邻冰塞之间或是冰塞与河岸之间;环流区域环流旋度沿水深线性增大,非环流区域环流旋度则线性减小,同一位置的不同流层环流旋度大小分布基本一致,弯道后半段大于前半段,弯顶前凹岸侧大于凸岸侧,最大环流旋度位于弯顶凹岸侧,约为0.91。

In order to analyze the subglacial flow structure and circulation distribution characteristics in a river bend,the flow field in the Shisifenzi bend was measured using acoustic Doppler current profiler(ADCP).By measuring the ice thickness,water depth and velocity of the bend,the ice condition and the distribution of the subglacial circulation in the bend section were analyzed.The results show that the flow under the ice in the bend does not completely present a double helix structure.During the freezing period,the circulation is concentrated on the concave side of the bend top and the convex side of the bend top,which is easy to occur between adjacent ice jams or between ice jams and river banks.The circulation curl in the circumfluence region increases linearly along the water depth,while the circulation curl in the non-circulation region decreases linearly.The distribution of circulation curl in different flow layers at the same position is basically the same.The circulation curl in the second half of the bend is larger than the first half and its value in the concave bank side is larger than the convex bank side,with the maximum circulation curl value of about 0.91 located in the concave bank side of the bend.