无坎宽顶堰闸孔自由出流流量系数的推求与验证

针对传统宽顶堰闸孔自由出流流量系数计算公式在大开度、接近堰流情况下流量系数偏小的问题,采用理论分析与试验相结合的方法,研究了无坎宽顶堰在平板闸门与弧形闸门条件下闸后收缩断面水深的变化规律,提出了新的基于闸后水流收缩断面特性来确定无坎宽顶堰闸孔自由出流流量系数的计算公式,并对该流量系数公式进行合理性验证。结果表明,所提公式计算所得无坎宽顶堰闸孔自由出流流量系数符合实际,且流量在大开度下与堰流情况接近、衔接良好。

Experimental and Theoretical Study on Gated Free Flow Discharge Coefficient for Broad-crested Ridge-free Weir

On the condition of large opening and the outlet flow close to weir flow, the traditional discharge coefficient usually appears to be small. In order to acquire the conform-to-reality discharge coefficient, experiments were carried out on both plain batten gate and segment gate of broad-crested ridge-free weir. Factors affecting the vertical contraction coefficient were firstly examined, and then the mathematical analysis was made to acquire the changing relationship of discharge coefficient based on the contraction characteristics of gate section. Finally, the formulas of discharge coefficient of both plain batten and segment gate were obtained. The results show that the pattern of gated free flow discharge is consistent with actual situation, especially in light of large relative opening.