Sluice
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A sluice is a water channel that is controlled at its head by a gate. A sluice gate is traditionally a wooden or metal plate which slides in grooves in the sides of the channel.
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Operation
Raising a sluice gate allows water to flow under it. (The term sluice gate refers to any gate that operates by allowing water to flow under it.) When a sluice gate is fully lowered, water sometimes spills over the top, in which case the gate operates as a weir.
Usually a mechanism drives the sluice gate up or down. This may be a simple, hand-operated, worm drive or rack and pinion drive, or it may be electrically or hydraulically powered.
The gates of a lock may work in a way similar to the way a sluice gate works, but traditional canal lock gates are hinged to swing like double doors.
Flow calculation
The sluice flow rate formula is:
- <math>Q = AC\sqrt{2gh}<math>
where:
- Q is the flow
- A is the area of the sluice
- g is the acceleration due to gravity on the Earth's surface (approx. 9.81 m/s²)
- h is the head across sluice
- C is the discharge coefficient (typically 0.61 for small depth ratios)
Types of sluice gates
- flap sluice gate - a fully automatic type, which is controlled by the pressure head across it. It is a gate hinged at the top. When pressure is from one side, the gate is kept closed. A pressure from the other side opens the sluice when a threshold pressure is surpassed.
- vertical rising sluice gate - a plate sliding in the vertical direction, controlled by machinery.
- radial sluice gate - a structure, where a small part of a cylindrical surface serves as the gate, supported by radial constructions going through the cylinder's radius, continuing through to a counterweight.
- rising sector sluice gate - also a part of a cylindrical surface, which rests at the bottom of the chanel and rises by rotating around its centre.