Pump Failure: Effect of Wall Elasticity on Pressure Fluctuations

The mechanical behaviour of the pipe wall material plays a major role in determining the pressure response of a fluid system during transient events. In regards to the behaviour of plastic pipes, such pipes have been widely used in water supply networks. This paper investigates and compares, numerically, the pressure response of a polyethylene high density (HDPE) pipe and a rigid steel pipe in case of exposure to transient events. The governing equations of the system are two coupled nonlinear hyperbolic partial differential equations, continuity, and momentum. The classical water hammer theory was used in the numerical modelling. The initiation of the hydraulic transients in the network was caused by a sudden centrifugal pump failure. The numerical resolution of the pressure-discharge equations is performed using the method of characteristics. The pressure fluctuations in polyethylene pipelines were found to be delayed in time compared to rigid pipes. The delayed wave celerity in polymeric pipeline is an asset for damping transient waves over time.