双向环形水槽流速分布规律试验研究

Experimental study on velocity distribution of two-direction rotating annular flume

环形水槽以其能满足细颗粒泥沙沉降所需的距离要求、无流入口和流出口的影响已被广泛使用在细颗粒泥沙运动规律的研究中。为最大程度地削弱横向流,采用环形槽、剪力环同时反向旋转,拟合出剪力环和环形槽的最佳转速比曲线,并在清水率定的过程中采用旋浆式流速仪测量不同水深、多级转速下环形水槽的分层流速。试验数据表明环形水槽中线处垂线流速分布呈S型,流速在边界处有较大的梯度,在流场中心区域分布较均匀,可用三次函数进行拟合。流速沿槽宽呈线性分布,由外壁向内壁递减,使得各断面流速分布相同,可以模拟无限长直水槽。

Annular flume has been widely applied in the research of the laws of sediment motion for its favorable features：it satisfies the long distance required in the settlement of fine sediment without influence of inflow and outflow.Reduction of secondary flow can be achieved by rotating the channel and the top ring of the flume in contrary directions.A proper selection of the speeds of the channel and the ring is provided in this study.When calibrating rotation rate in clear water,a propeller current meter is used to measure the layering current velocity of the annular flume,under different water depths and rotating speeds.Based on experimental data analysis,it can be seen that the vertical velocity distribution of the annular flume follows the S-shape distribution law.There is a larger velocity gradient at the boundaries,while in the main core of the flow field,the velocity gradient remains gentle and a cubic function formulas can be used to fit it.The radial distribution of velocity is linear and the velocity decreases from the outer edge to the inner edge,which leads to the same distribution of each cross section,so that the flume flow has the chance to match the idealized concept of an endless channel flow.