中文摘要：

根据为通过在这个工作的以前的学习获得的一个垂直的锋利的孔的流动的孔分泌物系数的试验性的数据，为小孔的流动机制的一个理论标准(viz。厚墙的孔和嘴) 并且大孔(viz。薄墙的孔) 基于孔直径的比率被建议到板厚度。它能帮助在不同操作政体下面为二流动机制在流动过程解释机械精力损失的驱散。象孔直径，板厚度和液体头那样的主要参数被相关，并且为孔系数的一个半实验的模型和有在稳定的区域的高精确的一个实验模型被开发。

英文摘要：

According to the experimental data of the orifice discharge coefficient for the flow through a vertical sharp-edged orifice obtained in the previous study of this work,a theoretical criterion for flow mechanisms of small orifice（viz.thick-walled orifice and nozzle） and large orifice（viz.thin-walled orifice） was proposed based on the ratio of orifice diameter to plate thickness.It can help explain the dissipation of the mechanical energy loss in the flow process for the two flow mechanisms under different operating regimes.The main parameters such as orifice diameter,plate thickness and liquid head were correlated,and a semi-empirical model for orifice coefficient and an empirical model with high precision at the stable region were developed.