主机与螺旋桨激励下某型散货轮船体振动差异特性研究

Difference Characteristic Analysis of Cargo Ship Vibration Caused by Low-speed Diesel Engine and Propeller

船舶的低频振动与水下辐射噪声是船舶最主要的噪声源,该振动噪声频谱通常分布在80 Hz以下的频段内,该频段内噪声源主要由主机激励和螺旋桨激励两部分构成。利用有限元法,基于某30 000 DWT型散货轮实际船型的尺寸和主机的安装位置建立带有主机、轴系、螺旋桨的船体有限元分析模型,进行模态分析,得到整船的固有特性。并在此基础上,分别计算主机机座垂向激励和螺旋桨轴向、垂向激励下整船的振动传递函数,获取两激励源引起船体振动的差异特性,为船舶动力系统设计与船体振动噪声控制提供参考。

Low frequency vibration of ship hull and underwater radiation noise are the main noise sources of ships. This vibration usually can be found in the low frequency range below 80 Hz, which is mainly caused by diesel engine exciting force and propeller exciting force. In this paper, the finite element model of a real 30 000 DWT cargo ship was established. This model includes diesel engines, shaft system, propeller and hull of the ship. Modal analysis was done for the model and the natural frequencies of the ship were obtained. On this basis, the vibration transmission functions of the ship hull caused by the diesel engine and the propeller exciting forces were analyzed and the characteristic of the ship vibration caused by these forces were studied. The results can be used as a database for ship propulsion system design and vibration control.