Pipe system diagnosis and leak detection by unsteady-state tests. 1. Harmonic analysis

Abstract

Since leak reduction actually corresponds to the acquirement of new water quality resources, development of leak detection methodologies is a non-trivial scientific and engineering issue for the water resources community. In this paper and in the companion paper it is shown that unsteady-state tests can be used to pipe diagnosis and leak detection. Specifically, in this part the governing equations for transient flow in pressurized pipes are solved directly in the frequency domain by means of the impulse response method. The analytical expression of the piezometric head spectrum at the downstream end section of a single pipe system during transients is then derived. Within this approach it is shown that the piezometric head spectrum is the product of two terms: the former related only to the maneuver characteristics, the latter depending only on the characteristics of the system. In the case of fast linear closure maneuvers, the analytical expression of both terms is also given. The derived analytical solution of the pressure signal in the frequency domain, allow us to interpret the data acquired in a single pipe system to have information on its state. Experimental data are compared to the analytic solution.