Author(s): Jost Pekolj; Anton Bergant; Kamil Urbanowicz

Linked Author(s): Anton Bergant

Keywords: No Keywords

Abstract: The presence of entrapped air poses a risk to the operational safety of hydraulic pipeline systems (hydroelectric power plants, water supply systems). It can significantly increase pressure surges during transient events such as filling and emptying of pipelines, hydraulic turbomachine start-up and stop, or even in steady state operation. Air is typically entrapped at high points in the pipeline profile or close to the pipeline devices (gate, valve, turbine, pump). A simple hydraulic pipeline system containing a trapped air pocket downstream the in-line valve is studied using dimensionless analysis. Following a sudden in-line valve opening, pipeline filling can generate large pressure oscillations, which may exceed the driving pressure of the reservoir. Key parameters influencing the hydraulic response are identified and combined into dimensionless groups. For a selected range of parameters, novel dimensionless charts of pressure peaks are included to enhance the understanding of water-air interactions and to provide a practical reference for dimensionally similar hydraulic systems. Such charts can help in the initial design and risk assessment of pipelines with entrapped air without the need for detailed numerical modelling. The relationships between the dimensionless groups in this study are derived from numerical simulations of a one-dimensional rigid water column model.

DOI: https://doi.org/10.1088/1755-1315/1561/1/012038

Year: 2025