Performance assessment of correlation methods for the velocity estimation of vibro-acoustic signals propagating in fluid-filled pipelines

In this paper, an assessment of an assortment of cross-correlation based methods for the estimation of the velocity of propagation of vibro-acoustic waves along fluid-filled metallic pipelines is presented. All methods are studied under the premise of utilization in a Time-Difference-Of-Arrival (TDOA) approach for the signal’s speed estimation, that leverages the expected time delay in the signal’s pickup by consecutively installed sensors, due to the travel time spent as the acoustic signal spreads along the examined pipeline. Two popular, frequency domain cross-correlators are investigated, namely the Phase Transform (PHAT) and the Hassab-Boucher (HB), along with the baseline time domain cross-correlation algorithm. An inventory of acoustic data - captured by a vibration monitoring rig during a series of leak signal data gathering experiments, conducted on an existing pipeline installation - is utilized for the investigation of the performance of each method and the illustration of the comparative results. The far-reaching target of the ongoing study, that encompasses the current work, is to derive a cross-correlation based, acoustic method for leakage localization on metallic pipelines carrying hydrocarbon products.