摘要
[目的]发现了一种螺旋桨噪声新成分——螺旋桨低频弹性被激发而形成的声辐射,特别是桨叶同相模态被激发引起的强烈声辐射,我们称之为“水母模态”,由其激发诱导的推进器轴系艇体系统低频窄带声辐射,并称为“水母效应”。为揭示其形成机理,开展螺旋桨低频固有振动特性研究。[方法]基于精细网格有限元方法分析螺旋桨的模态特征,得到空气和水介质中螺旋桨模态特性以及桨叶失谐对模态特性的影响规律;引用循环对称结构振动理论,对数值计算结果予以进一步验证。[结果]结果表明,在空气和水介质中,螺旋桨振动模态具有分组特征以及组内呈现出单频、重频模态的特征;桨叶失谐对重频模态影响较大而对单频模态/振型影响较小;精细化有限元计算结果与循环对称结构理论分析一致。[结论]本研究揭示了螺旋桨的低频模态特性,为螺旋桨低频噪声机理分析和控制提供了理论支撑,具有理论和工程应用价值。
[Objectives]We found a new component of propeller noises which is induced by the excitation of the low-frequency elastic mode of the propeller.In particular,the model where all the blades of a propeller vibrate in the same phase is stimulated will result in strong acoustic radiation.We have named the mode shape in which all the blades of a propeller vibrate in the same phase as"Jellyfish Mode".Also,the low-frequency narrow-band sound radiation of the propulsion system induced by the excitation of"Jellyfish Mode"is named by the"Jellyfish Effect".To reveal its mechanism,a study of the low frequency intrinsic modal characteristics of the propeller is carried out.[Methods]the refined mesh FEM method is utilized to study the dynamic feature of the propeller.The modal characteristics of the propeller both in air and water are obtained and the influence of the structural detuning of the propeller on the modal characteristics is analyzed.Then,the cyclic symmetric structure vibration theory is cited to validate and further study the low-frequency dynamic property of the propeller.[Results]The research revealed the grouping modal characteristics of the propeller both in air and water.Furthermore,the single frequency mode and repetition frequency mode characteristics in a mode group are also brought out.The research results showed that the structural detuning of the propeller has a great effect on the repetition frequency mode while it has little effect on the single frequency mode.The refined mesh FEM numerical analysis results are consistent with the theoretical results.[Conclusions]The study revealed the low frequency natural dynamic characteristics of the propeller and the research above can provide theoretical supports for propeller noise analysis and control,which is of great significance in theoretical and practical engineering.
作者
吴崇建
王春旭
陈志刚
杜堃
雷智洋
WU Chongjian;WANG Chunxu;CHEN Zhigang;DU Kun;LEI Zhiyang(China Ship Development and Design Center,W uhan 430064,China;National Key Laboratory on Ship V ibration and Noise,w uhan 430064.China)
出处
《中国舰船研究》
CSCD
北大核心
2020年第3期75-80,共6页
Chinese Journal of Ship Research
基金
装备发展部专项预研基金资助项目(1501JZJZ0304)。
关键词
螺旋桨噪声
水母模态
循环对称结构
单频模态
重频模态
失谐
propeller noise
Jellyfish mode
cyclic symmetry structure
single frequency mode
repetition frequency mode
structural detuning
