Underwater Sound Characteristics of a Ship with Controllable Pitch Propeller

The time-dependent spectral characteristics of underwater sound radiated by an ocean vessel has complex dependencies on ship machinery, propeller dynamics, hydrodynamics exhaust and motion, as well board activities. Here the a equipped with controllable pitch (CPP) is analyzed quantified via its (i) power density for signal energetics, (ii) temporal coherence machinery tonal sound, (iii) amplitude-modulated cavitation noise. Frequency-modulated (FM) signals are also characterized in terms their frequency variations. These compared different ratios ranging from 20% to 82% at fixed revolutions per minute (RPM). efficacy robustness parameter estimation pitches discussed. Finally, analysis one special measurement provided, when changes speed, RPM over duration measurement. 50% found be crucial point this about which attain peak values, while broadband associated coherences minimum. findings here elucidate effects variation ships propellers applications design noise mitigation.