engleski

Techno-economic assessment of new marine engine development with high noise and vibration performance

It is well known that noise and vibration are problems that are inherent to almost all ships. This is particularly emphasized in case on small ships, passenger vessels and large cruise ships. This thesis deals with noise and vibration problems onboard cruise ships that are primarily induced by four stroke diesel engines. Namely, the most of the presented research results was performed during the 3-month visit of the author to the engine producer Wärtsilä. Moreover, the investigation performed within this thesis is an initial part of long-term research project which is being performed by Wärtsilä with an aim to develop an engine with low emissions of noise and vibration. In this sense, the main issue is whether the prescribed noise and vibration levels should be achieved by conversions of existing engines, or completely new engine should be developed. Also, it is to be found whether only treatments on the engines are enough, or there are some modifications on ship structures that should be undertaken. In this work an overview of noise and vibration problems in ships is given. Basic principles of their propagation within the structure are described, together with brief description of measurement techniques. Requirements of Classification Societies on Comfort Class are analyzed in details as well as the measured full-scale results from the existing engines/ships. The relation between improvements in engine quality and comfort class is established. The influence of vibration levels on cabin prices is analyzed taking into account realistic data of cruise ship fleet. Finally, a simplified noise model is generated and analyzed by the hybrid Statistical Energy Analysis in order to specify most dominant influence parameters onboard, that should be changed to achieve lower noise levels. Together with thesis concluding remarks, recommendations for further research are given.

noise and vibration, main engine, Classification Society, comfort class, Designer-NOISE, source-path-receiver model

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