Air Conditioning Noise Prediction And Acoustic Design Of Ship Cabin

Noise level is one of the evaluation indexes of ship cabin environment, and the limit requirements to the ship cabin noise is set by the international marine organization. Noise prediction is the basis and premise of noise control and acoustic design. This thesis measures the main source of ship cabin noise—air conditioning system, and investigates in detail the calculation methods of the cabin noise prediction as well as acoustic design methods with setting the noise of the ventilation pipe as the source.Firstly, the marine air conditioner fan’s internal and external sound pressure as well as sound intensity are measured. The research is started with the noise source analysis and severe sound leakage problems at the front surface are found. As a result, the highest sound power appears at this surface. At the same time, the ventilation pipe’s noise was taken to calculate the ship cabin noise as a boundary condition.Secondly, the cabin structure is modeled by Ansys software, and then is imported into Virtual.Lab Acoustics software to calculate its value in the sound field. With a comprehensive consideration of modes analysis and field point pressure comparison, an available emulating method is proposed. Then, the cabin noise caused by air conditioner fan is predicted, and the frequency spectrum character of field point pressure is concluded for guiding and improving the cabin acoustic design.Finally, the effects of different marine air conditioning system design on the ship cabin noise level are investigated, at the same time the regulation about how the location of the air distribution device as well as the acoustic design of the ventilation pipe influence the results are concluded. Additionally, based on the former analysis, a satisfactory result on how to reduce the noise level through cabin acoustic design is obtained.