Author(s): Jim C. P. Liou, Bruno Brunone, Silvia Meniconi
Linked Author(s): Chyr Pyng (Jim) Liou
Keywords: Analytical approximation, field data, friction, line drafting, water hammer.
Abstract: Consider a pipeline that supplies water to a constant-head reservoir. Subsequent to a sudden inlet flow stoppage, there is an immediate Allievi-Joukowsky head drop at the inlet. This is followed by a period of line drafting during which a more gradual but sustained head drop continues for a 2 L/a seconds, where L = length of the pipeline and a = water hammer wave speed of the water-pipeline system. The inlet head at 2 L/a seconds is the lowest of the entire water hammer episode and is of interest in certain applications. Because friction affects water hammer in a complicated way, quantification of line drafting is usually accomplished through numerical solution of the governing equations for one-dimensional transient flow. This study presents an analytical method to obtain the head at the inlet as a function of time for 2 L/a seconds after the flow stoppage. An equation to directly compute the minimum head at the pipeline inlet is also presented. The validity of the analytical results is evaluated by six sets of measured data on pump shutdown transients in a steel rising water main of Recanati, Italy
Year: 2017