Abstract

This paper presents an analysis of the potential effects on pressure transients of air entrained at the downstream end of entrapped air pockets followed by a hydraulic jump in pressurized pipelines. For this purpose, a methodology is followed to identify the potential locations, where air pockets can be found along the pipeline, to compute the air-void fraction downstream of the air pockets and the volume of the pockets, respectively. Further, the calculations were carried out using a numerical model based on the methods of characteristics and the Lax-Wendroff. A case study of an existing pumping system was considered to validate the methodology proposed. The results show that small air pockets cause an important enhancement of the maximum pressures throughout the pipeline profile, conversely pressure transients are significantly reduced with increasing air-pocket volumes and bubbly flow air content.