Optimization of irrigation pipelines design for minimizing the effects of water hammer phenomenon

Abstract EN

The rapid change in velocity of a fluid in a closed pipeline system can generate large pressure waves of large amplitudes which can propagates through the system with the speed of sound.

This is called the water hammer phenomenon which causes the additional pressure in the pipeline system which may cause rupture of pipes and damage of pumps and valves.

It creates also a reduction in pressure values which can argument the separation or the cavitations effects.

This research aims to study and analyze this phenomenon during sudden power failure, pump trips without control devices the attached to PVC pipeline systems of pressure classes PN4, 2000m length with diameters 450, 500, 560, 630, 710 and 800mm and flow rates 1200, 1350, 1500, 1650 and 1800 m3/h with elevation differences of 40m.

The analysis will be done for the same pipeline data with PN6 and PN10.

The steady state pressures were obtained and Joukowsky equation used to calculate the maximum and the minimum pressure, the results were compared with the permissible pressure classes for the pipeline PN4, PN6 and PN10, then the dissection for the need of control devices will be taken.

This research provided complete design for PVC pipeline PN6.

The pipeline length is 2000m, elevation difference of 40m and discharge 1200m3/h.

Theoretical and CFD (AFT impulse) analysis provides to determine the values of transient pressure during power failure.

Design criteria for system equipment and control devices such as (air vessel, surge tank.

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), at an adequate economical analysis had been done to estimate the optimum diameter that ensures a minimum total cost.

A result led to 560 mm was found as the optimum diameter.

The analysis shows that installing of air vessel or surge tank is must this can be mitigated the high pressure to be less than 6 bars and controlled the magnitude of the negative pressure to safe limits can be changed to positive pressure.