中文摘要：

通过实验，考察了Reynolds数、液层高等操作参数和孔径、板厚等结构参数对垂直锐边孔口自由出流特性的影响。在此基础上，根据孔流系数曲线的不同规律，将孔流机理划分为“大孔机理”和“小孔机理”，并对孔流曲线进行了分区讨论，借助边界层理论，探讨了这两类孔流过程的机械能损失差异以及孔流曲线在不同操作区的机械能损失差异。

英文摘要：

The effects of Reynolds number, liquid head, orifice diameter and plate thickness on the flow characteristics of vertical sharp-edged orifice discharge were investigated experimentally. According to the distinct profiles of orifice discharge coefficient, it was found that the orifice discharge followed two mechanisms of “small orifice” and “large orifice”, and the orifice coefficients were analyzed regionally. The dissipation of mechanical energy in the orifice flow process with respect to “small orifice” and “large orifice” and the energy loss in different operating regimes were discussed on the basis of the boundary layer theory.