TOP SEALING RADIAL GATES DESIGN – SPECIAL CONSIDERATIONS

摘要

Radial gates are commonly used to control water flow at dams and in conduits, mostly because radial gates result in reduced gate operating force compared to vertical lift gates. There are two types of radial gates: crest type, with no top seal and orifice type, usually with two top seals, one mounted on the embedded frame (lintel plate) and the second on the gate. The lintel mounted top seal maintains contact with the gate skin plate as the gate moves up from the fully closed position, preventing the flow shooting from the top, when the gate is partially open. The gate mounted top seal helps better sealing of the gate when it is fully closed. The crest type is used at most spillways and is designed for maximum upstream water level coinciding with the top of the fully closed gate, except in case there is overtopping to be considered, with the gate fully closed. The orifice type is used both at spillways and in conduits, including power intakes and low level outlet works, depending on the project layout and economics compared to vertical lift gates. The orifice type gates have a breast wall on the upstream side to form the orifice and are high head gates, with high velocity flow under the gate. There are special considerations for the design of top sealing radial gates, as a result of high head acting on them and the need for sealing at the top when the gates are partially open. The paper addresses the special considerations and provides relevant explanations.