Generalized characterization of pipeline systems with air chamber through development of the dimensionless impedance response

Abstract

ABSTRACT An air cushion chamber is a feasible and efficient hydraulic device to control water hammer for pressurised pipeline systems. The introduction and evolution and hydraulic transient depend on distinct features of pipeline systems such as length, diameter and the property of pipeline extension as physical properties; flowrates, pressure, boundary conditions as hydraulic conditions; and interaction with surge protection devices (air chamber) as hydraulic conditions. Considering all factors simultaneously can be incredibly difficult, even for a simple air chamber pipeline valve layout. This study introduces the dimensionless transfer function and expression for air chambers in dimensionless frequency domain in order to effectively address the water hammer generation and its counteracting processes. To comprehensively characterize hydraulic transients for pipeline systems equipped with air chambers, two representative dimensionless parameters were used. Along the pipeline system, it is possible to develop a frequency-independent expression for hydraulic impedance. A comparison between the developed method and other existing methods (e.g. characteristic method and impulse response method) revealed excellent agreement. Application of the dimensionless parameters to systems with different dimensions and hydraulic conditions shows that the proposed dimensionless parameters can address substantial ranges of real systems.