Lock Gate
Water pressure on Lock Gates
Key Facts
Gyroscopic Couple: The rate of change of angular momentum () = (In the limit).- = Moment of Inertia.
- = Angular velocity
- = Angular velocity of precession.
Blaise Pascal (1623-1662) was a French mathematician, physicist, inventor, writer and Catholic philosopher.
Leonhard Euler (1707-1783) was a pioneering Swiss mathematician and physicist.
Overview
Whenever a dam or a weir is constructed across a river or canal, the water levels on both the sides of the dam will be different. If it is desired to have navigation or boating in such a river or a canal, then a chamber, known as lock, is constructed between these two different water levels. Two sets of gates (one on the upstream side and the other on downstream side of the dam) are provided as shown in fig - 1.MISSING IMAGE!
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MISSING IMAGE!
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- P = Water pressure on the gate AB or BC acting at right angles on it
- F = Force exerted by the gate BC acting normally to the contact surface of the two gates AB and BC (also known as reaction between the two gates), and
- R = Reaction at the upper and lower hinge
- H1 = Height of water to the left side of the gate.
- A1 = Wetted area (of one of the gates) on left side of the gate
- P1 = Total pressure of the water on the left side of the gate
- H2, A2, P2 = Corresponding values for right side on the gate
- RT = Reaction of the top hinge, and
- RB = Reaction of bottom hinge
Example:
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Example - Water pressure on lock gate
Problem
Two lock gates of 7.5m height are provided in a canal of 16m width meeting at an angle of . Calculate the force acting on each gate, when the depth of water on upstream side is 5m.
Workings
Given,
- Height of lock gates = 7.5m
- Width of lock gates = 16m
- Inclination of gates =
- H = 5m
Solution
Force acting on each gate, P = 1133 KN