Coherent optical fiber interferometric sensor for incipient cavitation index detection

Abstract

Optical fiber sensors (OFSs) are nowadays widely adopted in many different fields and applications. Cavitation in pipeline systems is one of the main concerns of engineers because of its serious consequences for the lifetime of pipelines and on the performance of hydraulic devices. Among other useful parameters the incipient cavitation index is one of the most important because it represents the very beginning of the phenomenon. The present paper discusses the possibility of using optical fiber technology to detect cavitation in a pipeline. The experimental system exploits an interferometric fiber optical sensor based on a coherent demodulation scheme, avoiding the need for working point stabilization systems and coping with the polarization fading. Several dispositions and geometries for the sensors have been tested to select the most efficient solution. The results are then compared with cavitation indexes calculated following the standard procedure, using accelerometer measurements, to prove the optical fiber sensors’ effectiveness.