The effects of resonances on time delay estimation for water leak detection in plastic pipes

Abstract

In many water distribution systems, metallic pipes are being replaced by plastic pipes due to their deterioration and age. Although acoustic methods are effective in finding leaks in metallic pipes, they have been found to be problematic with plastic pipes due to the high damping within the pipe-wall. In acoustic correlation methods, sensors are placed either side of a suspected leak, and the peak in the crosscorrelation function of the measured signals gives the time difference(delay) between the arrival times of the leak noise at the sensors. To convert the time delay into a distance, the speed at which the leak noise propagates along the pipe (wave-speed) needs to be known. It has been found the structural dynamics of the system can corrupt time delay estimates. In this paper, data from test-rigs in the United Kingdom and Canada are used to demonstrate the problems encountered, and a model is developed to further investigate which of two commonly used correlation algorithms are more robust to the presence of resonances in buried pipe systems. It is found that this is highly sensitive to the bandwidth over which the analysis is conducted. Moreover it is further found the Phase Transform (PHAT), which is frequently used for leak noise detection, is particularly sensitive to the presence of resonances, whereas the basic cross-correlation (BCC) function is found to be more robust.

More information

Identifiers

Catalogue record

Export record

Altmetrics