明渠测流长喉槽结构优化及设计理论研究

Design and Structure Optimization of Long Throat Flume

长喉槽是一种水头损失小 ,测流精度高 ,结构简单的明渠量水建筑物 ,是一种新型的量水建筑物 ,目前的计算理论存在如下缺陷 :没有考虑侧向收缩造成的局部水头损失的影响 ;没有确定水头损失最小的进口收缩比 ;没有确定最佳的体型设计参数。该文通过一系列的水力学实验 ,确定最优收缩比为 1∶ 3;最佳运行范围为堰上水头与喉长的比值为 0 .0 7～ 0 .7;设计流量时的设计取值为 0 .6 ;并对收缩段水头损失的计算公式进行修正。通过以上改进 ,量水公式误差由 5 %减小到 1.5 % ,淹没可达 0 .92 8。

Long throated flume with an advantage of less head loss, higher precision of flow measurement and structures easy to be built, has not been researched completely, and it is a new kind of flow measurement structure. But defects still exist in the theory associated with computation. Firstly, the effect of local head loss caused by end contractions was neglected. Secondly, the contraction coefficient of inlet section is not presented. Thirdly, the optimum shape of structures is not determined. Through a series of hydraulic experiment, the contraction coefficient is determined to be 1∶3. The ratio of sill referenced head to the throat length for best performance is 0.07～0.7 which is suggested to be 0.6 for design. The formula to calculating head losses in the contraction section were revised. And the corresponding error decreases from 5% to 1.5%. The modular limit is up to 0.928. And a long throat flume CAD software system was developed.