Further investigation on the water-hammer control branching strategy in pressurized steel-piping systems

Abstract

The branching design strategy was recognized as being a practical technique for water-hammer surge control in pressurized steel-piping systems. This strategy is based on adding a branched polymeric short-section at the transient sensitive region of an existing steel piping system. On the other hand, design practices require numerical solvers that are both accurate and computationally efficient. Accordingly, this paper revisited the implementation of the branching design strategy using a 1-D unconventional water-hammer model based upon the Ramos formulation to benefit from its simplified representations of unsteady friction effects and pipe wall behavior. The transient solver was performed using the Fixed Gird Method of Characteristics (FG-MOC). The transient solver effectiveness was demonstrated by comparing the obtained numerical results with pertinent experimental ones quoted in the literature; further, computational savings were significantly carried out via the selected formulation. The proposed design strategy was implemented within two kinds of boundary conditions initiating water-hammer up- and down-surge waves. In addition, two types of polymeric materials, including high- or low-density polyethylene (HDPE or LDPE), were utilized for the branched short-section. Results evidenced the potential of the branching design strategy to attenuate excessive pressure -rise and -drop, while safeguarding existing pressurized piping system configurations. Furthermore, the study of the dependency of the short-section material and size on the attenuation rate of pressure -rise and -drop evidenced that a higher wave speed of the branched short-section provided a higher attenuation rate of pressure -rise and -drop, and helped estimate near-optimal values for the short-section length and diameter.