Detection of anomalous operation of driveline components in a cavitation tunnel for marine propellers

The present study makes use of microphonic and accelerometric measurement techniques to identify the cause of an anomalous behavior of the driveline of a cavitation tunnel for marine propellers. Such a testing facility makes possible the fluodynamic and acoustic characterization of in scale models of naval propellers. To get significant data it is mandatory for the acquisitions that the test facility operates in optimal conditions, limiting as much as possible any type of emission of noise not associated to the propeller under test. Recently, noise originating from the driveline requested an investigation on its causes to locate the elements constituting its source. To identify and to characterize the failure, both microphonic and accelerometric measurements were performed. With reference to the first typology of measurements, an acoustic mapping in three dimensions was adopted, making possible to locate the mostly critical driveline zones and to individuate the possible components having an anomalous operation present in the driveline. In addition, in the same time accelerometric measurements have been done to acquire structural information on the driveline itself. The correlation between the vibrational data and the acoustic ones made possible to obtain additional elements useful to complete the diagnostic study on the system.