انجمن هیدرولیک ایران نشریه علمی هیدرولیک 2345-4237 6 1 2011 05 22 Water Hammer in Polyethylene Pipes ضربه قوچ در لوله های پلی اتیلن 69 84 85505 10.30482/jhyd.2011.85505 FA علیرضا کرامت علی حقیقی استادیار ‌گروه عمران، دانشکده مهندسی، دانشگاه شهید چمران اهواز Journal Article 2011 03 23 This research aims to model the dynamic viscoelastic effects of polyethylene pipes under waterhammer<br />pressures. As known, following the water hammer event, a cyclic loading and unloading due<br />to the pressure fluctuations occurs. Loading on polymeric materials results in deformations that unlike<br />the elastic materials do not immediately return after unloading. This retarded behaviour gradually<br />reduces the wave speed causing to a different transient response. Herein, the viscoelastic effects of<br />polyethylene pipes on the transient flow is numerically simulated and studied using the Kelvin-Voigt<br />model. The developed model is then verified using some experimental data from the literature.<br />Afterwards, a simple hypothetical reservoir-pipe-valve system is defined to investigate several aspects<br />of viscoelasticity. It is concluded that in a standard water hammer caused by valve closure, the<br />minimum pressure head is more affected by viscoelasticity than the maximum one. Furthermore, with<br />the increase of initial flow, viscoelasticity takes part more to damp out the destructive dynamic effects<br />of water hammer. This makes the viscoelastic properties of polyethylene pipes to be figured out as an<br />adaptive procedure to automatically alleviate the water hammer issues in water supply systems. https://jhyd.iha.ir/article_85505_3874d57b5a59876de6f38c5cebdc932a.pdf