Cavitation noise modulation in a model-scale propeller under non-uniform inflow: A time-frequency and cyclostationary perspective

This study elucidates how cavitation dynamics govern the acoustic modulation features of a model-scale propeller under non-uniform inflow. A five-bladed high-skew propeller was tested in a cavitation tunnel under various hydrodynamic conditions to generate representative cavitation regimes, including suction-side sheet, tip vortex, pressure-side sheet, and combined cavitation. Hydroacoustic signals were acquired using a hydrophone setup and analyzed through time-frequency as well as cyclostationary techniques. Specifically, amplitude modulation features were extracted via a multi-band decomposition and Enkurgram-based filtering framework to identify cavitation-related components from broadband interference. The results reveal that suction-side sheet and tip vortex cavitation significantly enhance mid-to-high-frequency broadband noise, accompanied by pronounced cyclic modulations associated with blade passing events. In contrast, pressure-side cavitation exhibits weak modulation and minimal spectral amplitude. These findings provide experimental insights into the acoustic signatures of different cavitation states and support the development of underwater noise control and detection technologies.