Application of spectral kurtosis to the detection of tip vortex cavitation noise in marine propeller

• Detecting tip vortex cavitation in propeller is of importance for commercial or military purposes.
• Impulsive noise characteristics induced by cavitation was extracted by spectral kurtosis.
• Following DEMON analysis pointed out the presence of cavitation.
• Illustrations were given by experimental measurements in water cavitation tunnel.

In marine propeller, the tip vortex cavitation and its relevant noise has been the subject of extensive researches up to now. Among the most cases of experimental approaches, accurate and objective detection of cavitation inception is primary, which is the main topic of this paper. While radiating an explosive-bursting noise into the surrounding medium, the cavitation occurs whenever the propeller blade passes through so-called wake-peak zone. Likewise the faulty bearing cases, hence, periodic occurrence of bursting noise induced from tip vortex cavitation provides a confirmative diagnostic proof, whereby the DEMON analysis(DEtection of envelope MOdulation on Noise or sometimes referred as Envelope analysis) can be effectively employed.Recently, the concept of spectral kurtosis significantly resolved an enhancement of such impulsiveness in a signal with a strong additive noise, which is a prerequisite for the DEMON processing. By taking advantage of the benefit, this paper deals with its applicability to the detection of tip vortex cavitation in propeller. For an acoustic measurement in water cavitation tunnel, the optimum filtration band from 65 kHz to 130 kHz could be obtainable by the spectral kurtosis. Also subsequent DEMON analysis showed a satisfactory result in detecting the cavitation inception.