Noise & Vibrations
This subprogramme is focused on developing knowledge and tools on the prediction of noise and vibrations. The focus in radiated noise prediction is not only limited to predicting the hydrodynamic excitation, but also on predicting the radiated noise levels at arbitrary positions in the flow-field.

Mission
Predict and verify propeller induced-vibrations for comfort on board and radiated noise with respect to detection and interference with marine wildlife.

State of the art
Measurements of propeller-induced hull-pressure fluctuations have been carried out in the Depressurized Towing Tank (now Depressurized Wave Basin) for many years. The design of a new propeller is often focusing on getting the maximum efficiency, but the maximum allowable propeller-induced pressure fluctuations are limited.
With regards to vibrations, current practice is to make an assessment of the risk of vibrations on the basis of an excitation force, which is obtained by integrating the pressure fluctuations over a certain area of the aft ship. This force is then compared to an empirical criterion.
Research on underwater noise is just starting up. MARIN is in the process of determining the acoustic characteristics of the DWB.

Vision 2016
Predict hull-pressure fluctuations and radiated noise with known uncertainty and accuracy using model scale measurements and (semi-empirical) computational tools, obtain a methodology to predict the vibration nuisance based on the same tools and obtain a methodology to determine underwater radiated noise based on on-board measurements.

Vision 2020
Improved prediction of hull-pressure fluctuations and radiated noise from model tests and semi-empirical computational tools in combination with a prediction based on cavitation predictions by CFD, both linked to a validated method for prediction of vibration hindrance in an early design stage, but also have an established procedure for underwater radiated noise based on on-board measurements.

Collaborations
In the context of this research programme, MARIN is, or has been, working on the following JIPs:

Example applications
  • Prediction of radiated noise using a combination of DWB tests and computations for a cruise ship that will sail in noise-sensitive areas.
  • Prediction of underwater radiated noise using full scale on board measurements for fishing vessels without the need for a noise measurement range.
  • Predicting risk of vibration for a high-comfort class ferry from measured of computed hull-pressure fluctuations.
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