掺气坎后空腔长度是检验掺气效果的一项重要指标，主要受掺气坎体型（即坎高和坡比）、水力条件、空腔内负压以及空气阻力等因素影响。本文采用物理模型试验，研究了缓坡条件下泄槽底坡、掺气挑坎体型对空腔长度的影响，得出了弗氏数Fr、雷诺数Re、韦伯数We三者分别与空腔长度的关系，并分析了缓坡条件下空腔长度随Fr波动这一试验结果产生的原因。最后运用杨永森公式对空腔长度进行了计算，并分析了计算值与试验值之间的误差和相关性。研究成果可为优化掺气设施设计和完善经验计算公式提供参考。

The cavity length in the aerator is an important indicator for aeration effects. It is impacted by many factors, including the aerator shape (height and slope), hydraulic conditions, negative pressure in the cavity, and air resistance. In this paper, the physical model experiments were conducted to study the effects of chute slope and aerator shape on the cavity length under the conditions of slight slope. Furthermore, the relationships between the cavity length and each of the three factors, namely Froude number (Fr), Reynolds number (Re), and Weber number (We), were obtained, and the reason of the experiment results that the cavity length fluctuates with the Froude number (Fr) under the conditions of slight slope was analyzed. Finally, the cavity length was calculated using Yang Yong-sen’s formula, and the errors and correlations between the calculated and experimental values were analyzed. These results can provide references for optimizing the aerator design and improving the empirical calculation formulas.

国家自然科学基金（51069002、51269005）；云南省自然科学基金（2009ZC015M）