新型梯形量水堰水力特性试验及数值模拟

梯形量水堰因结构简单、测流精度较高而广泛应用在灌区末端渠道上,但现有灌区梯形量水堰存在的测流范围小、泥沙易在堰前淤积问题严重制约着其应用推广,据此提出以改进堰为基础的堰孔组合的新型梯形量水堰.采用量纲一化分析法确定流量公式,并以水工模型试验结果为基础,率定数值模拟模型参数,利用Fluent软件计算获得4种新型梯形量水堰不同流量条件下的水深、堰流流量值、流速分布及速度矢量图,最后通过试验数据拟合出测流公式.结果表明:不同孔口高度的新型梯形量水堰孔口出流对堰上出流的影响随着堰前总水头的增大而逐渐减小;拟合的流量公式简明易用且通用性较高,平均相对误差为2.63%;将模拟结果与试验值做对比分析,二者吻合度较高,平均相对误差为2.53%,说明模拟结果具有一定的可靠性,可为堰孔组合式量水设施的工程设计提供参考依据.

Experiment and numerical simulation on hydraulic characteristics of novel trapezoidal measuring weir

Trapezoidal measuring weir is widely used in the end channels of irrigation area because of its simple structure and high flow measurement accuracy. However, the existing trapezoidal measuring weir in irrigated areas has the problems of small flow measurement range and easy deposition of sediment in front of the weirs, which seriously restrict its application and popularization. Therefore, based on the improved standard weir, a new type of trapezoidal measuring weir was proposed. Dimensional analysis method was used to determine the basic pattern of flow formula. Based on the results of hydraulic model experiment, numerical simulation model parameters are calibrated. The water depth, weir flow value, velocity distribution and velocity vector diagram of four new trapezoidal measuring weirs under different flow conditions are obtained by using Fluent software. Finally, the flow measurement formula is fitted by the experiment data. The result shows that the influence of the orifice outflow of the new trapezoidal measuring weir with different orifice heights on the outflow of the weir decreases with the increase of the total head in front of the weir. The fitted flow formula is simple and easy to use, with an average relative error about 2.63%. By comparing the simulation results and that of expe-rimental results, it is found that they are in high degree of agreement with average relative error of 2.53%, which indicating that the simulation results have a certain reliability, and can provide basis for engineering design of weir hole combined water measuring facilites.