Tackling of hydraulic cavitation in pressurized pipe flow using high- or low-density polyethylene penstock and short-section

Abstract Recent studies have proved that the utilization of polyethylene (PE) short-section or penstock is a promising water hammer control tool. However, the interplay between the magnitude attenuation and the phase offset of pressure-wave oscillations remains challenging. This study aimed at inspecting the capacity of a dual PE penstock/short-section-based control technique, with regard to the aforementioned interplay. In this technique, a PE penstock was lumped to the transient initiating zone of the main pipe and a short-section of the counter extremity of the pipe was replaced with PE. The transient pressure-wave behavior in a gravitational viscoelastic pipe involving cavitation was described by the extended 1D water hammer equations embedding the Vitkovsky and Kelvin–Voigt add-ons. The numerical solution was performed by the fixed grid method of characteristics. The high- (HDPE) and low-density (LDPE) were demonstrated in this study. Analysis revealed that upgrading techniques based on LDPE enabled a desirable tradeoff between the magnitude attenuation and the phase offset of pressure-wave oscillations. Particularly, the dual penstock/short-section specific upgrading technique allowed a more important attenuation magnitude of pressure peak (or crest), and led to a similar expansion of the wave oscillation period. Furthermore, results evidenced that the proposed technique outperformed the renewal of the original piping system.