城市雨水口流场及紊动特性试验研究

Experimental study on flow field and turbulence characteristics of street inlet

基于具有上下两层结构的城市洪水综合试验平台,使用三维超声多普勒流速仪(ADV)测量较大水深条件下雨水口周边流速与紊动强度的三维分布.试验结果表明:当来流水深较大时雨水口中心会出现一地漏漩涡,来流与漩涡共同作用引起雨水口周边流速显著增加.漩涡中心处流速相对较大且流速纵向分量与来流方向相同侧平均流速大于相反侧,各试验工况条件下最大流速均位于雨水口下游边缘附近.雨水口引起的漩涡增大了水体的紊动强度,紊动强度的平面分布与流速平面分布较为类似,工况2条件下平均湍流动能由水槽进口处0.004m2/s2增加至雨水口下游边缘处0.145m2/s2.水体剧烈的紊动效应使底床摩阻的影响相对减弱,流速沿垂线呈常数型和线性型分布,不符合明渠水流对数型的分布特征.

Based on the urban flood experiment platform,the three-dimensional acoustic doppler velocimetry(ADV)was used to measure the distribution of flow velocity and turbulence intensity near the street inlet under the condition of large water depth.The experimental results show that a vortex appears in the center of the street inlet when the inflow depth is large enough.Due to the interaction of inflow and vortex,the velocity in the center of the vortex is greater than that in the edge,the longitudinal velocity of the vortex points to the downstream side is greater than to the upstream side and the maximum velocity of each layer is located near the downstream edge of the street inlet.At the same time,the vortex caused by the street inlet greatly increases the turbulence intensity of flow.In case 2.the depth-averaged turbulent kinetic energy of flow increases form 0.004 m2/s2 at the upstream of the flume to 0.145 m2/s2 at the downstream edge of the street inlet.The effect of intense turbulence relatively weakens the influence of bottom friction,thus the vertical distribution of velocity follows the constant and linear law,which does not conform to the logarithmic distribution characteristics of the open channel flow.The above test results can fully reflect the flow field and turbulence characteristics around the street inlet,and provide a reference for the design optimization and numerical simulation.