Development of a design procedure for the prediction of structure-borne noise generated by the reciprocating machines installed on board ships

往复式机械是船舶振动和结构噪声的主要来源。往复式机械产生的振动能量在低频和高频范围内通过船舶结构传递到起居舱甲板，降低了乘客的舒适度，增加了船员暴露在噪音和振动中的机会。此外，通过舰船结构传递的振动能量会转化为水下噪声，影响海军舰艇的声学特性，增加影响海洋生物的水下噪声污染。为了将污染源与船舶结构隔离，发动机和辅机通常弹性安装。这种解决方案将噪声和振动源与船体结构解耦，并降低了声源传递给接收结构的振动能量。尽管这一解决方案被广泛接受和使用，但正确的解耦系统设计及其实际应用却更加复杂。一个有效的源和接收结构之间的耦合设计应该考虑源、隔离系统和接收结构的动态特性，以及这些部分之间的相互作用。到目前为止，船级社的规则和国际标准为设计者提供了有效的程序来设计往复机械和接收结构之间的解耦，从动态的角度来看，仅在低频范围内。关于结构噪声水平，目前还没有有效的预测程序，也没有提供任何标准的限值。这项建议研究开发一种新的设计程序，用于预测船舶往复机械产生的结构噪声。这一程序将以数值模型和分析公式为基础。一个新的模型将在纪念大学创建。该模型将再现船用柴油机基础的典型结构，并将进行实验测试，以验证数值模型和分析公式的有效性。在本研究活动中将开发的设计工具面向船舶设计师和船舶顾问。使用这些工具，他们将能够在新船设计的早期阶段预测往复式机器产生的结构噪声，找到有效的解决方案来降低船上的整体噪声水平。这将增加乘客的舒适度，减少船员暴露在危险噪音水平下，并允许海军舰艇的设计者控制船只的声学特征。

Reciprocating machines are prominent sources of vibration and structure-borne noise on board ships. The vibrational energy generated by reciprocating machines, in the low and high frequency range, is transmitted through ship structures to accommodation decks, decreasing the comfort level for passengers and increasing the exposure to noise and vibration of crewmembers. Moreover, the vibrational energy transmitted through ship structures translates into underwater noise, affecting the acoustic signature of navy ships and increasing the underwater noise pollution that affects sea life. In order to isolate the sources from ship structures, engines and auxiliary machines are usually resiliently mounted. This solution decouples the source of noise and vibration from ship structures and decreases the vibrational energy transmitted by the sources to the receiving structures. Even though this solution is widely accepted and used, a proper design of the decoupling system and its practical application is more complex. An effective design of the coupling between the source and the receiving structures should take into account the dynamic characteristics of the source, isolating system, and receiving structures, as well as the interactions among these parts. To date, classification society rules and international standards provide the designers with effective procedures for the design of the decoupling between reciprocating machines and receiving structures, in the dynamic point of view, solely in the low frequency range. Regarding the structure-borne noise level, no effective procedures are available for its prediction, nor are any standard limits provided. This proposal investigates the development of a new design procedure for the prediction of the structure-borne noise generated by reciprocating machines on ships. This procedure will be based on numerical models and analytical formulations. A new mock-up will be created at Memorial University. The mock-up will reproduce the typical structures of a marine diesel engine foundation and experimental tests will be carried out to validate the numerical models and the effectiveness of the analytical formulation. The design tools that will be developed in this research activity aim at ship designers and ship consultants. Using these tools, they will be able to predict the structure-borne noise generated by reciprocating machines in the early phases of the design of a new ship, identifying effective solutions to reduce the overall on-board noise level. This will increase the comfort for passengers, decrease the exposure of crewmembers to hazardous levels of noise, and allow the designers of navy ships to control the acoustic signature of the vessels.