Hyperbolic localization of incipient tip vortex cavitation in marine propeller using spectral kurtosis

Incipient tip vortex cavitation is one of the primary concerns for propeller design in commercial- or naval- vessels. This paper attempts its hyperbolic localization, which should be preceded by accurate estimation of time delay between measured acoustic signals. Although the generalized cross-correlation with phase transform can be considered as a conventional algorithm for time delay estimation, it is prone to be vulnerable to the noise dwelling outside the frequency band of signal. In order to nullify these noise effects, a weighting function, resembling the rectangular window in frequency domain, is introduced. By further noting that the signal arisen by the tip vortex cavitation can be categorized into the cyclostationary type, the spectral kurtosis is adhered to design the optimum band of the frequency weights. Finally, the proposed method is shown to be valid by two experimental demonstrations of artificial source and propeller cavitation.