Rotary gate: Submerged flow condition

The rotary gate is a recently proposed gate for application in semicircular elevated irrigation networks. In this study, the hydraulics of rotary gate submerged flow was theoretically and experimentally investigated. Two approaches for estimating the submerged flowrate were considered, namely the stage-discharge based on the superposition rule and the dimensional analysis principles. The results revealed that the gate opening angle and the submergence ratio affect the submerged discharge the most. Based on the compiled experimental data relationships for estimating the discharge in such flow conditions were presented. Statistical analysis indicated that both approaches yielded satisfactory results for discharge estimation. Also, the submerged threshold condition of the rotary gate was investigated and a relationship was proposed whose results concurred with the observed data. In addition, the gate discharge coefficient and its head loss were studied and relationships for determining the discharge coefficient and the relative head loss in submerged flow condition were proposed. •The hydraulic performance of the rotary gate; a novel structure, proposed for installation in semicircular canals, as a flow regulation, distribution and measurement structure, was investigated in the submerged flow condition which is vital for field application.•The hydraulics of rotary gate submerged flow was theoretically and experimentally investigated. The results revealed that the gate opening angle, the submergence ratio and deviation from modular limit affect the submerged discharge and the modular limit is affected by the opening angle.•Two approaches for estimating the submerged flow discharge were developed, namely the stage-discharge based on superposition principle and the pi theorem dimensional analysis based on Buckingham π theorem.•Relationships to determine the relative head loss of the rotary gate and submerged discharge coefficient of the rotary gate were developed.•A diagram similar to that of the well-known Henry's chart was presented which exhibits the variations of the rotary gate discharge coefficient with respect to the relative upstream and tailwater depths.