Experimental investigation of cavitating flow-induced vibration of hydrofoils

Abstract

The objective of this paper is to investigate the unsteady cavitation behaviors and corresponding cavity-induced vibrations. Experimental results are presented for NACA66 hydrofoils made of stainless steel and POM Polyacetate for various cavitation regimes. A simultaneous sampling technique is applied to analyse the transient cavitating flow structure and corresponding structural vibration characteristics. The results showed that the maximum vibration amplitude keeps relative small for the inception and sheet cavitation, increases dramatically for the cloud cavitation and declines for the supercavitation. As for the cloud cavitation regime, the trend of the vibration velocity goes up with the growth of the attached cavity, accompanied with small amplitude fluctuations, and decreases with large amplitude fluctuations. At the moment the cloud cavity breaks from the primary attached cavity, the vibration velocity hits the peak. As for the effect of hydroelastic response, the main vibration frequency for POM Polyacetate hydrofoil is larger than that for stainless steel hydrofoil due to the larger angle of attack caused by the twist deformation. The cavitation pattern for POM Polyacetate hydrofoil appears to be fragmentized, corresponding to the chaotic hydroelastic response of the hydrofoil, which is mainly attributed to the disturbance caused by the deformation and cavity-induced vibration.