桩群排列方式对水流结构特性的影响

利用室内水槽试验模拟了桩群不同排列方式工况下水流的运动规律,借助三维超声波多普勒测速仪(ADV)量测了不同断面、不同垂线、不同测点的时均流速,得到了不同工况下的流速分布、紊动强度、雷诺应力,并分析了它们的变化特征。结果表明:桩群使流速重新分布,在桩群区与非桩群区交界处流速明显减小,且桩群布置密度大时,水流绕流流速最大;当桩群排列方式改变时,各断面的三向紊动强度都会发生较大改变,但是对于某一方向上的紊动强度各断面仍有一定的相似性;修桩后雷诺应力分布规律有所不同,水流上侧的雷诺应力较大;桩群排列方式的改变不仅使雷诺应力沿程变化较大,而且改变了雷诺应力时均值的大小及最大值出现的位置。

Study on the Hydraulic Characteristics Influenced by Pile Group Arrangement

The article used the indoor tanks to simulate the different arrangement of pile groups under 4 different conditions of the tank water movement.With the ADV measuring in different sections,different vertical,and different points of time average velocity,the article obtained velocity distribution,turbulence intensity,Reynolds stress under different conditions and analyzed their variation.The results show that the pile groups redistribute the flow.At the junction of the pile group area and non-pile group area,the flow velocity significantly reduced.The larger pile group layout density is,the largest the flow velocity will be.When changing the arrangements of pile group,the turbulence intensity on each of the three sections will change greatly.And in a certain direction,the turbulence intensity is still a certain similarity.Reynolds stress distribution under building the pile groups is different from that in the ideal condition.The Reynolds stress in the upper layer is larger.The different arrangements of pile groups not only lead to Reynolds stress distribution along the direction vary considerably,but also change the time-average value of the Reynolds stress and the maximum value position.