Water Hammer: Gradual closure of valve, Sudden closure of valve considering pipe in rigid and Sudden closer of valve considering pipe elastic

Water Hammer

Consider a long pipe AB, connected at one end to a tank containing water at a height of H from the centre of the pipe. At the other end of the pipe, a valve to regulate the flow of water is provided. When the valve is completely open, the water is flowing with a

velocity, V in the pipe. If now the valve is suddenly closed, the momentum of the flowing water will be destroyed and consequently a wave of high pressure will be set up. This wave of high pressure will be transmitted along the pipe with a velocity equal to the velocity of sound wave and may create noise called knocking. Also this wave of high pressure has the effect of hammering action on the walls of the pipe and hence it is known as water hammer.

The pressure rise due to water hammer depends up on:

1. Velocity of flow of water in pipe.

2. The length of pipe.

3. Time taken to close the valve.

4. Elastic properties of the material of the pipe.

The following cases of water hammer in pipes will be considered.

1. Gradual closure of valve

2. Sudden closure of valve considering pipe in rigid

3. Sudden closer of valve considering pipe elastic.

Gradual closure of valve

Gradual closure of valve

Sudden closure of valve considering pipe in rigid

Sudden closure of valve considering pipe in rigid


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