Prediction of Critical Submergence for Horizontal Intakes Under Asymmetrical Approach Flow Conditions

Air-entraining vortices at intake structures present serious challenges to the functionality of water intake systems, resulting in reduced efficiency and possible damage to hydraulic equipment. The present study aims to predict the critical submergence, Sc, which is the minimum vertical distance between the free surface and intake pipe to avoid air-entraining vortices, for horizontal intakes under asymmetrical approach flow conditions. Dimensional analysis was utilized to investigate the influences of intake geometry, approach Froude number, intake Froude number, Reynolds number, and Weber number. Two hundred and twenty-five experimental data for asymmetrical approach flow conditions were evaluated to derive more general and accurate empirical equations predicting the dimensionless critical submergence, Sc/Di. The results indicate that the intake Froude number (Fr)i, and the geometric parameter are the most important parameters that affect Sc/Di. Accordingly, the most accurate empirical equations were obtained while considering all the flow and geometric parameters to predict Sc/Di. On the contrary, the accuracy of the empirical equations considering only (Fr)i gives moderate results in predicting Sc/Di.