Design,Optimization And Application Of Sound Package In The Ship

With the development of new energy and “green ships” technology,ship designer begins to consider the economic,environmental protection and comfortableness.Noise is one of the vital factors affecting those ship properties,it is becoming more and more important in ship design process.From the implementation of more stringent cabin noise standards by International Maritime Organization(IMO)in 2014,other classification societies have also issued relevant provisions about ship cabin noise.As a result,noise reduction has become a hot technology in shipbuilding industry.Acoustic package,as a new technology and new product to solve the problem of ship cabin noise,has been widely payed attention.This paper firstly studied the numerical methods of evaluating the acoustic performance of materials.The means of acoustic performance evaluation are mainly about three kinds,inclusing experimental method,numerical simulation and theory method.Numerical simulation is an important method for acoustic package design,which can avoid the high cost and long cycle.This paper puts forward the concept of numerical standing wave tube method and numerical reverberation chamber method,studies the different numerical simulation methods(SEA,FEM,BEM,FE+SEA)including the similarities and differences in applicable frequency and boundary conditions.On the basis,put forward a new method of material acoustic calculation,BEM+FEM+SEA hybrid method.This method integrates boundary element,finite element method and statistical energy methods’ advantages,maintains certain precision in the whole frequency band.At the end of first part,five numerical methods are sort out with specific examples,and some use advice is brought up.Secondly,sound package design and optimization with FEM+SEA and SEA method are studied.Design different types of acoustic package as the initial program,use the genetic algorithm method,with the sound of the material layer thickness as the variable,sound insulation quantity as the objective to optimize.Results show that optimization of acoustic package performance can be achieved by the combination of different variables,constraint conditions and objective conditions.At the same time,it is also found that the calculation and optimization results of the two methods are different,which needs further research.Thirdly,two problems of SEA method are studied in order to improve the accuracy of the calculation.On one hand,as the host vibration spectrum is measured on the base panel on foot,how to accurately simulate the actual situation of the host structure and load vibration in SEA model is an urgent problem.On the other hand,as multiple noise resources in ship,how to measure specific affection for certain cabin of every single resource is vital.For the first question,FEM model is adopted to translate the vibration from base panel to ship structure,and noise contribution rate is put forward to quantify the impact of single noise resource.Finally,the application of acoustic packet technology in ship is carried out.The study of main engine vibration noise can improve the calculation accuracy.The calculation of noise contribution rate makes noise-reduction proposals more targeted.Optimization of acoustic package allows better sound performance.On the basis,the above research results are applied to the actual ship,specific acoustic package is carried out for the noise reduction in certain cabin with high noise contribution rate.