低Fr数流动跌坎掺气槽的水力及掺气特性

The hydraulic and aeration characteristics of low Froude number flow over a step aerator

通过模型试验和理论分析， 研究了低Ｆｒ 数（ Ｆｒ＜ ７） 流动情况下空腔积水对跌坎掺气设施水力及掺气特性的影响． 建立了计算跌坎掺气设施水力及掺气特性的预测数学模型． 给出了射流出射角的修正式； 积水尺寸的计算式； 掺气设施实际运行工况（ 空腔长度、空腔负压、掺气量等） 的预估方法． 研究表明， 低Ｆｒ 数流动情况下， 由于重力作用显著， 积水对水力及掺气特性均有显著影响．

The effect of water contained in cavity to hydraulic and aeration characteristics of step aerator in low Froude number flow(Fr<7) is investigated experimentally and theoretically. The mathematical model for predicting the hydraulic and aeration characteristics of aerator is established and the correction for the emergence angle of the jet is deduced. The expressions for calculating the volume of the water contained in cavity, length of cavity, pressure in cavity and the air entrained are proposed. It is concluded that the water contained in cavity may significantly affect the characteristics of flow and aeration.