A new hydraulic transient calibration model

Abstract

Water utilities undertake modelling of the hydraulic behaviour (i.e., steady state and transient (waterhammer) conditions) of pipeline assets to identify high pressures and flows and locations were potential weaknesses may be exposed (e.g., to predict where bursts may occur). Furthermore, new or renewed pipeline infrastructure is being constructed at an accelerated rate as existing systems deteriorate and new sources of potable water (e.g., desalination and re-use plants) are connected to existing pipelines. The capacity of existing pipelines to withstand in-situ and changing hydraulic conditions as old pipes deteriorate and new pipes are connected to systems is an important issue for water utilities. Research conducted with the South Australian Water Corporation and United Water between 2001 and 2007 has involved the measurement of a large sample of transient (waterhammer) events (i.e., a large sample of hydraulic transient pressures). These events have been subsequently modelled using the traditional form of analytical engine applied commonly in proprietary software. The results have shown that mechanical damping dissipates transient energy via motion and vibration at flexible joints, non-rigid restraints and to variable soil conditions (for buried pipelines). This paper presents, as an example, the results of one of the transient tests conducted on a small network in South Australia and attempts to model the response of the network using a traditional model. A new model for estimating the response of field pipeline systems to hydraulic pressures, involving the calibration of a conceptual transient model, is described and significantly improves the accuracy of the transient analysis.