Investigation Of Water Cabin Noise Prediction And Assessment Of Fish Farming Boat

Fish farming boat is a closed aquaculture platform for salmon and large yellow croaker with high added value at far-reaching sea.Water tank are the sites of fish and also at the heart of the fish farming boat.Surrounded by a large number of equipment,the water tank will be influenced adversely by the equipment noise propagated through the structure,air and water,thus hindering the growth of fish and reducing the economic efficiency of fish farming boat.In order to make the noise environment in the water tank meet the standard of fish growth,it is necessary to forecast and evaluate the noise of the cabin and reduce the noise of the tank exceeding the standard.In this paper,empirical formula,CFD technology and acoustic finite element method were used to study the excitation source of the fish farming boat.Then acoustic finite element technology(FEA),statistical energy analysis(SEA)and FE-SEA hybrid analysis were used to calculate the low,high and middle frequency noise in the water tank.In the end,noise reduction is carried out for the cabin exceeding the standard by comprehensively considering the deck auxiliary materials,insulation material layout and illustration of muffler.The specific research content is as follows:(1)Research on methods for screening of complex excitation sources and determination of noise characteristics of excitation sources was carried out.The principles of sound source screening under the influence of complex excitation sources were determined.The equipment is divided into two types according to whether it is unique equipment of the ship: conventional sound sources and special sound sources.The method for determining the noise data and spectrum characteristics of the sound source is summarized,and the noise characteristics of the main excitation sources of the ship are determined by the comprehensive use of empirical formula,noise superposition principle,CFD technology and acoustic finite element method.(2)The method of water tank noise prediction,the space and frequency distribution of water cabin noise are studied.Combined with the general cabin noise prediction theory and the characteristics of water cabin noise prediction,a set of noise model establishment and prediction methods suitable for large water cabin are summarized on the basis of noise prediction software VAOne.Noise in the water cabin is predicted by this method,the spatial and frequency distribution of the cabin noise is obtained,and the reason for the spatial distribution of the cabin noise is explained from the perspective of energy flow.The contribution degree of noise in different frequency bands to the total sound pressure level is obtained.(3)In terms of noise control method research,combined with noise contribution rate analysis,maximum energy transfer path analysis,sound absorption and insulation technology and noise reduction technology,a set of noise control methods suitable for large water cabin is summarized.The high-and mid-frequency noise of water cabin with noise exceeding the standard is processed by this method.The research shows that after the noise reduction,the mid-and high-frequency noise is significantly reduced,and the synthesized total sound pressure level basically meets the noise standard,which verifies the feasibility of the method in reducing the noise of the water cabin.