Influence of the reduced frequency on the 2-D partial sheet cavitation behaviour for a foil in a gust

ABSTRACT This paper presents a numerical study of the influence of the reduced frequency on the 2-D partial sheet cavitation behaviour for a foil operating in a gust. The cases of continuous and intermittent cavitation are investigated. The analysis is based on the Boundary Element Method (BEM). Results are presented for a NACA16-006 foil moving through transverse gusts at varying reduced frequencies. For continuous cavitating flow a sinusoidal varying velocity field is considered, and for intermittent cavitating flow a ship wake peak type of gust is investigated. A comparison is made between a fully unsteady model and a quasi-steady analysis using a modified angle of attack, such that the loading is the same for both analyses. The latter is found to well predict the cavity length but not the cavity dynamics. The influence of the wake peak width on the maximum cavity length was found to be significant mainly through the effect on the unsteady foil loading. The maximum cavity length correlates well with the maximum lift coefficient of the wetted flow. The effect of the peak amplitude on the cavity length is non-linear and increases with the reduced frequency.