New stage-discharge relationships for radial gates

Calibration of gates under free and submerged flow regimes is a classical hydraulic problem. In this paper dimensional analysis was applied to investigate both free and submerged flow conditions through a radial gate. The original Ferro’s method for submerged flow regime was modified by introducing the maximum allowable tail water depth permitting free flow. Based on Buckingham theorem and applying the Incomplete Self Similarity (ISS) concept different forms of the dimensional equations were proposed. According to the current available experimental data the most accurate dimensionless formula was proposed. The proposed dimensional equation not only is more accurate than the original Ferro’s method but also can be applied for free to submerged flow conditions continuously and through the transition zone. Finally, a new Discharge Reduction Function (DRF) which is applicable for other water measuring structures and gates working under submerged flow condition was identified.