Hydraulic performance of sluice gate with unloaded upstream rotor

Abstract

This study presents video analysis of the hydraulic performance of a sluice gate with an unloaded upstream built-in rotor. A number of laboratory experiments were  conducted using two unloaded rotor shapes. The first was the cross-shaped rotor and the second was the Savonius-like rotor. A new video analysis technique was  introduced for measuring rotor angular speed and its perturbation. Swift speed  cameras and Tracker software were used to measure the upstream backwater depth and to estimate the instantaneous variation of the rotor speed. The study shows that adding a rotor upstream of the gate caused the upstream water level to increase  such that the averaged normalized afflux increased to 1.72 and 0.9 for the cross-shaped and the Savonius rotors, respectively. Lab experiments indicated that the water flow–structure interaction for the sluice-rotor is quite complex and nonlinear. Two main flow regimes were distinguished. The flow regimes are: the flow through a rotor with possible weir flow conditions and the orifice flow conditions. The  time-averaged angular speed of the tested Savonius-like rotor ranged between 0 and 300 r/min. As the upstream backwater depth increased, the angular speed  increased; however, the rate was significantly lower for the orifice flow condition compared to the flow under rotor and weir flow conditions. The video analysis also indicated that significant perturbation exists for the rotor angular speed. The  normalized perturbation intensity varied from a minimum of 8% to a maximum of 60%.

Keywords: sluice gate, rotor, angular speed, video analysis, hydropower