Research On The Accurate Prediction Of The Inner Cabin Noise

In recent years,the comfort performances of vessels have reached a very high level.The ship cabin noise is an important factor affecting the comfort.The environment on board is complex.If the cabin noise is controlled after construction,there will be many problems including the high cost,the long period is,and the poor effect is.Therefore,it is very necessary to predict cabin noise and put forward improvement measures in the design stage.This paper mainly studies the influence of construction technology and indoor facilities on the sound field distribution in the room.Besides,it calculates the noise of different positions in a large conference room of an engineering ship,which makes the prediction of cabin noise more detailed.Firstly,compare the simulation results of LMS Virtual.Lab to the theoretical values and classical experiments and verify the correctness of the research route in this paper.Then,using the boundary element analysis method in LMS Virtual.Lab Acoustics module,study the influence of the wall openings,cracks and facility layout on the distribution of indoor sound field.As for the openings and cracks,study on the area(from small to large)and location(center,edge and corner),establish different acoustical model of the room and then obtain the indoor noise level.As for the facility layout,the following works have been done:(1)Comparing and studying the sound field distribution in no seats and with sound absorption seats conditions.(2)Under the indoor point source and outdoor plane wave source respectively,when the sound barrier is placed horizontally and longitudinally,the change of indoor field point sound pressure level.(3)Study the effect of vertical,Y and T type sound barriers' sound insulation.(4)Establish the acoustic boundary element model of ventilation holes in different locations to predict the sound pressure level of indoor field points,and give the recommended installation location.Finally,taking an engineering ship as an example,establish the acoustic model of the whole ship based on the statistical energy analysis method to predict all cabin noises,as a result of obtaining the average sound pressure level in each acoustic cavity.Then choose the large conference room on the captain's deck.Use the LMS Virtual.Lab software to establish its acoustic boundary element model including ventilation holes,louvers,seats,tables and whiteboards.Predict the sound field inside accurately and obtain sound pressure distributions at different heights.