Acoustic Design Of Vessel Ventilation System And Research On The Control Of Cabin Noise

With continuous improvement of shipbuilding technical requirements,more and more attention has been paid to the problem of ship vibration and noise.For the accommodation far away from the engine room,the main noise comes from fan noise transmitted by the ventilation system and the aerodynamic noise generated by the air flowing through ducts and valves.The noise seriously affects the efficiency of work and rest and physical and mental health.Therefore,it is necessary to carry on the acoustical design to the ventilation system of ship in order to reduce the level of cabin noise.In this paper,the teaching system of marine central air conditioning in the auxiliary machine Laboratory of Wuhan University of Technology is used as the object.The acoustic simulation and measurement experiment are carried out and the effective and feasible noise reduction measures are put forward on this basis.The main contents include:(1)First of all,the cold and wet loads are calculated by reference to the air conditioning design manual and the supply air volume is determined accordingly.On the basis of its boundary conditions,the steady state calculation is carried out to the flow field by using FLUENT.Then,its result is taken as the initial value and carried out transient state calculation with DES turbulence model.Next,the calculation results are exported.Finally,the acoustic calculation is carried out in LMS Virtual.Lab Acoustics and.At last,we get the sound field distribution and analyze its characteristics and regularity of changes(2)According to the simulation of the air-conditioning room,an enclosed space model is set to calculate its acoustic modes.Then,the acoustic response of the whole sound field is calculated in the modal space under the given sound source.Next,the measurement experiment of the noise of acoustical room was carried out.Noisy data is collected at selected 12 monitoring points.Finally,compare experimental data with the simulation value.Suitable excitation source and acoustic mode order is selected by means of mathematical analysis.(3)To use a method for acoustic impedance of porous absorbing material in impedance tube,the acoustics simulation is carried out based on the boundary condition of that result.According to the overall sound pressure of each measuring point,the optimum flow resistivity,thickness,space position and area of porous absorption material are selected.In order to find out reasonable,economical and practical noise reduction measure,this article plans to design the combination of suspended absorber and porous absorbing material.