基于FLOW-3D的明渠壅水断面流速特征研究

Study on Flow Velocity Characteristics of Backwater Section in Open Channel Based on FLOW-3D

随着传感器技术的发展,渠道流量测量技术有了新的突破,目前渠道流速大多是根据点流速进行计算,但在渠道内因阻滞作用的影响,同一断面上的水流速度分布会随着水深的不同而不同。为探讨不同水深边界情况下,明渠剖面流速分布特性。文章截取某梯形渠道100 m渠段,利用FLOW-3D进行建模,模拟了不同的下游壅水情况。通过对不同水深情况下剖面流速分布的研究,采用固定流速系数的方法进行分析,给出了在壅水高度小于20 cm的情况下,可以达到测量精度(误差不超过±10%)的水流速度系数。通过模拟计算,拟合出了水流速度系数随水深变化的曲线,对流速系数进行修正后可使测流误差小于1.40%。

With the development of sensor technology,the channel flow measurement technology has a new breakthrough.At present,the channel flow velocity is mostly calculated according to the point flow velocity.However,the distribution of water velocity on the same section varies with the depth of water because of the blocking effect in the channel.In order to study the characteristics of velocity distribution in open channel section under different water depth boundary conditions,a 100 m trapezoidal channel section is intercepted and FLOW-3D model is used to simulate different backwater conditions downstream.Based on the study of velocity distribution in profile under different water depths,the method of fixed velocity coefficient is used to analyze the velocity distribution.The results are given when the backwater height is less than 20 cm,the flow velocity coefficient with measurement accuracy(error not exceeding±10%)can be achieved.The curve of flow velocity coefficient varying with water depth is fitted through simulation calculation.The error of flow measurement is less than1.4%after the velocity coefficient is modified.