Pipe surge and water hammer experiment

However, in the experimental graph Fig 3.

Water hammer pdf

To adhere to both requirements, the surge tank must be a 2-way flow tank. The pipe thickness and possibly pipe material could have been non-uniform. This reduces the amount of bubbles formed. The inaccurate readings could be caused by the loosening of the copper coils of wire when the experiment was started. Similarly, we can feed water into the pipe in the case of a negative surge flow. To illustrate the water hammer effect, imagine water in a pipeline being suddenly stopped due to closure of a valve. Surge vessels depend on pipe friction to bring the pipeline to a steady state. It was suggested by Dawson and Fox that the accumulation of minor changes in the flow during the transient period contributed to the higher pressure peak in the case without air entrainment.

Upon reaching the end of the pipeline, the wave reflects and travels in the opposite direction towards the valve again, and the process repeats itself. By changing factors affecting the variables in the governing equation, pressure surge can be reduced.

Pipe surge and water hammer experiment

Frequently, the pressure surges can cause problems, ranging from noise and vibration to more major instances such as pipeline collapse Fig 1a and 1b. This shortfall in reading can be explained by the following factors.

Ideally, the check valve should shut instantaneously and remain closed right when flow reverses Lee, In addition, the use of surge tanks in industries can convert water hammers into mass oscillators.

The pipe thickness and possibly pipe material could have been non-uniform.

surge pressure calculation

This is because vibrations are reduced, reducing the turbulence in the flow. This is because the air bubbles can absorb some of the pressure surge that the fluid might experience.

difference between pipe surge and water hammer

Lastly, air can enter the pipeline through falling jets of fluid into the sump from the inlet Lee,which is commonly accompanied by vortex formation. Burrows and Qiu reinforce that although a large cavity can suppresses large pressure excursions and act as an accumulator, the large volume shared among multiple pockets could intensify peak pressures, depending on where the air pockets in the pipe are.

Other reasons for the discrepancy could be due to the following experimental errors.

Surge tanks water hammer

From the experiment however, both the actual values differ considerably. To slow down the flow in the pipes, flywheels could be installed near the pumps. In addition surge vessels convert pressure transients into mass oscillation Balluto, All three pressure sensors are connected to a conditioning unit with USB connection for direct connection to a PC not supplied. Lastly, with every oscillation, there is a lower pressure surge. The time delay between the sensors can be used to determine the speed of sound through the water that is attenuated by the elasticity of the metal pipe wall. Both the values of 9. Fig 2: Pressure transient at valve following instantaneous valve closure without friction Taking into account friction and friction recovery, the pressure transient more realistically resembles Fig 3. From Fig 3. We could use flywheels to slow down these flows, which can be detrimental to the system. Air entrainment in the form of bubbles can lead to the formation of vortices. The pressure transducer may have been reused many times previously before the experiment.

Boulos, Don J.

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Surge analysis experiment report