Study On The Prediction Of Shipyard Cabin Noise With Statistical Energy Analysis

Shipboard vibration and noise are the important aspect in ship design and building. This is not only due to the requirement of national and international rules, but also due to a growing interest in reducing annoyance and discomfort to the crew and passengers. However the shipboard is a complex system, especially the shipboard cabin noise, which is difficult to be solved. So it is important to predict shipboard cabin noise in complex system.In this paper, predicting shipboard cabin noise is studied by statistical energy analysis (SEA) as follows:First of all, numerical analysis of the 3-D ship acoustic model is built by using statistical energy analysis method, and the simulation result is compared with the sailing test. The results show that, if the turbulence fluctuations excitation is not considered, the prediction noise would be smaller, so the turbulence fluctuations excitation should be calculated. If acoustic model don't contain the shipyard outfitting material, the simulation result will be higher than the real value. Making the shipyard outfitting material into the acoustic model is advised, so that the simulation result can be precise. Basing the ship cabin noise with statistical energy analysis, choosing spring reducing vibration equipment in this paper is effective action.Secondly, the arrangement of superstructure is crucial for shipboard noise control. The proper configuration of accommodation space, engine room and funnel is very important to the noise levels on board. The influence of the different arrangements of the superstructure on shipboard noise is discussed in this thesis. Four kinds of arrangement are studied in detail. The SEA method is used to build the system models for predicting noise and vibration level on shipboard for different arrangements. The structureborne noise and airborne noise are calculated and the noise paths are diagnosed based on the SEA models. The proper arrangement is recommended based on the numerical results.Finally, numerical analysis of the 3-D ship acoustic model is built by using statistical energy analysis method. The results show that, if the engine room is laid by damping material, its noise would not be reduced, but and the other cabin noise would be reduced, and the effect of free damping material is better, as compared with constraint damping material. If the cabin where is not any exciting source is laid by damping material, we can see noise reduce in the acoustic space, and the constraint damping material works better than the free damping material. The calculation also displays that the acoustic excitation quite obviously affects the sound level of the cabin in which the acoustic excitation exists, and the structure excitation obviously impacts the cabin which is far from the structure excitation. There is only a little action on noise reduction by stiffened plate, and there is no action on noise reduction by the ballast water and ballast oil.