Noise Prediction Of Fishing Vessel’s Cabins And Study On Noise Influencing Factors

With the implementation of Code on Noise Level on Board Ships on July 1,2014,by the International Maritime Organization(IMO),the problem of ship noise and its control issues have received more and more attention in ship design and manufacture.And research on noise transmission,noise reduction and sound absorbing materials have become more and more extensive.Noise prediction in the ship design can effectively save the cost of noise reducing measure after the ship is finished.Noise reduction is not only important for large ships,but also more influencing for small and medium-sized ships such as fishing boats.In this paper,a noise prediction software based on statistical energy method is used to predict the cabin noise,and the influencing factors of noise are also analyzed.Firstly,the noise of a 49 m ocean-going seiner is predicted and the principle of the statistical energy method and its main parameters are introduced in details.And the standard of ship cabin noise is also introduced.Through the simulation,the noise prediction value of the living compartment is calculated,and compared with the reference value given by the noise code.Then,some noise reduction suggestions are proposed for the cabins which have higher noise.Besides,the noise in the engine room area and the main cabins of the superstructure was compared between two situations,whether cabins have inboard water or not.The results show that inboard water has little effect on the noise of the cabins of the superstructure.Secondly,a superstructure model is established and the cabin noise with the influence of different arrangements of the cabins structure is studied.Through numerical simulation,the noise of different layout schemes of the superstructure including the problem of the upper and lower bulkheads,the size and arrangement of the single-story cabins and the overall layout of the entire superstructure without changing the height,are calculated.And the differences of noise prediction values under these layout conditions are studied.The results show that,when the superstructure of the ship is distributed evenly,and when the number of cabins is more,the noise can be reduced at a certain extent.Finally,the difference in the sound absorption effect of the composite materials is investigated.A composite material based on rock wool is taken as the research object,and only the thickness and porosity of rock wool are changed to study the differences of noise values.It is found that the sound absorption and noise reduction performance of the composite does not change linearly with thickness and porosity under the excitation which have specific lower noise in low frequency.And there is an optimum value for it to reduce noise.The result for laying method research show that the laying order of the material has a great influence on the noise value and noise is most closely related to the outermost material.In a word,through noise prediction and parameter sensitivity analysis of a cean-going seiner,in this paper,the influence of cabin partition and composite material on cabin noise is studied.It can provide reference for noise analysis in the designing of this kind of ship.