Experimental study exploring the interaction of structural and leakage dynamics

Strategies for managing leakage from water distribution systems require the ability to effectively evaluate such real losses through the understanding of the behavior of individual leaks, including their response to changes in pressure regime due to demand or management strategies. This paper presents the results from an innovative experimental investigation aimed at understanding the response of longitudinal slits in pressurized viscoelastic pipes, specifically considering the interaction between the structural and leakage dynamics. For the first time, leakage flow rate, pressure, leak area, and material strain were recorded simultaneously, providing new knowledge of the complex interaction of these factors. The paper shows that strain and area are directly related, hence it is possible to employ strain as a predictor of leak area, calculated using a calibrated viscoelastic model. Using such an approach, the leakage flow rates under a range of quasi-static pressures were accurately predicted and validated. Overall the paper demonstrates that the orifice equation, with a constant coefficient of discharge, is suitable for accurately estimating dynamic leakage flow rates from longitudinal slits, provided that the leak area is suitably incorporated.