Numerical Study on the Vibration and Noise Characteristics of a Delft Twist11 Hydrofoil

Abstract

Underwater radiated noise (URN) is greatly increasing due to an increase in commercial shipping, sonar activities, and climate change. As a result, marine life is having difficulty communicating, and marine ecosystem disturbances are occurring. The noise from the cavitation of propellers is affecting URN. Cavitation is a phenomenon in which rapid changes of pressure in a liquid lead to the formation of small vapor-filled cavities in places where the pressure is relatively low. This phenomenon results in poor efficiency of the propeller or turbine of a ship and noise, vibration, and erosion. For these reasons, this study examines the URN of sheet and cloud cavitation. A numerical analysis was done using a Delft Twist11 hydrofoil. The URN resulting from cloud cavitation and sheet cavitation was compared with the numerical results of previous studies. The results showed that URN normally increases due to pressure fluctuations when cavitation occurs. URN increased more significantly in conditions of cloud cavitation than in cavitation inception. It is also shown that a frequency begins to occur after the occurrence of the cloud cavitation, and the frequency grew as the cavitation fully developed.