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.
Highlights
This reduces the efficiency of the propeller and turbine, and the noise produced by the cavitation greatly affects the communication of marine life
Various organizations and committees, including IMO, MEPC, MSFD, and NORSOK, are making efforts to resolve problems related to Underwater Radiated Noise (URN)
The experiment was conducted at the cavitation tunnel of Delft University of Technology, and detailed research was conducted on cavitation features over time using Particle Image Velocimetry (PIV) according to the flow rate and cavitation number
Summary
The cavitation caused by a propeller rotating causes erosion of the propeller, vibration, and noise. Guidelines have been developed to regulate URN emitted by ships in the North Sea (SONIC, 2012), and the European Union have established ‘quietMED’ to address noise problems in the Mediterranean region. Studies on cavitation occurring from the propulsion of ships are needed. Foeth et al [1,2] did an experimental study on the cavitation features and frequency of hydrofoils. Hoekstra et al [3] compared and analyzed the results simulated by various institutions based on the results of the experiment by Foeth et al [2]. Bensow [4] conducted a numerical study on the cavitation features and frequency of a Delft Twist hydrofoil and compared the results for different turbulence models.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
