» Research Note « Head Loss of Transient Accelerating Flows for Pipes in Series

Document Type : Technical Note


1 MSc. Student, School of Water Science Engineering, Shahid Chamran University, Ahwaz

2 Professor, School of Water Science Engineering, Shahid Chamran University, Ahwaz


Creation of transient flow in closed conduit is a common phenomenon and also causes serious damage in water supply systems. Flow path leads the system to design of pipes in contraction and expansion series and also gradual and sudden changes in the cross-sections. These changes create negative pressures in pipes specially where pipe diameter changes. The main purpose of this study is experimental investigation of pressure-wave changes in pipes in contraction and expansion series specially where the diameter changes. Tests were carried out with different speeds of valve opening and the results showed that in pipes in contraction series, changes of pressure-wave speed due to pressure changes (that resulted from the opening of the valve at the downstream end of the piping system), at the locations where the diameter changes was more than sections near the valve.


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