The spiral casing in a hydropower plant is a large, spiral-shaped pipe that surrounds the turbine runner, mainly used in a Francis turbine. When high-pressure water comes from the dam through the penstock, it first enters this spiral casing. The casing spreads the water evenly around the entire circumference of the turbine so that all the blades receive equal force. As water flows around the spiral and gradually enters the turbine through guide vanes, the cross-section of the casing becomes smaller to maintain uniform pressure and velocity. This design ensures smooth and balanced rotation of the runner, which then drives the generator to produce electricity efficiently.
Stator Ring
Fixed circular part that holds and supports the internal guide system. It does not rotate.
Spiral Casing
Spiral-shaped outer housing that spreads water evenly around the turbine.
Cover Ring
Top ring that closes the turbine and prevents water leakage.
Support Ring
Bottom structural ring that supports and holds the turbine parts in position.
Stay Vanes
Fixed blades that guide water smoothly toward the turbine runner.
Turbine (Runner)
Rotating part with curved blades. Water hits it and makes it spin to produce power.
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