Innovative Noise Analysis Modeling Scheme Produces Results in Half the Time of the Traditional Method

Abstract

Abstract Because noise issues onboard marine and offshore structures can adversely affect the performance and health of crew members, the subject has gained increasing attention in recent years. Noise analysis is necessary to improve acoustic design and mitigate inappropriate noise. The innovative modeling scheme for noise analysis presented in this paper focuses on simplifying the noise modeling method. Case studies were conducted for an anchor handling tug supply (AHTS) vessel (Nam Cheong Limited 1st design project NCA80E – 64.8m 80t AHTS DE) and an 80,000 deadweight long-range product tanker to demonstrate the simplified modeling method. Noise analysis results were compared with the measurement data to validate the proposed method. Two models – including the whole vessel model and the simplified model, comprising only part of the vessel encompassing the accommodation block and engine room area – were analyzed under transit conditions using the statistical energy analysis (SEA) software Designer Noise. The analysis accounted for multiple noise paths from major noise and vibration sources, including airborne path, first structure-borne path, and secondary structure-borne path. The primary structures, compartments of interest, and outfitting were modeled to calculate the sound attenuation from the sources to the receiver rooms. Differences in the case study analysis results, calculated using the entire vessel model and the simplified model, are 0.03 dB for the AHTS and 0.17 dB for the tanker, which is negligible. Moreover, the analysis results of the simplified model are all higher than those of the entire model, which indicates that the simplified method is slightly on the conservative side. By comparing the analysis results of the simplified model with the actual measured noise levels of the AHTS for a total of 35 sites, it is found that 51.4% of the sites are within 3 dB, and 28.6% of the sites are within 3-5 dB, while only 20 % of the sites are larger than 5 dB. By comparing the analysis results of the simplified model with the actual measured noise levels of the tanker for a total of 48 sites, it is found that 60.4 % of the sites are within 3 dB, and 29.2% of the sites are within 3-5 dB, while only 10.4 % of the sites are larger than 5 dB. The proposed method can reduce the modeling time of the main hull by approximately 50% while still maintaining comparable accuracy.