柴油机结构振动和辐射噪声特性研究

集多体动力学方法、有限元方法、声学边界元方法于一体,对某柴油机结构振动和结构辐射噪声特性系统地开展了数值预测和分析工作。通过模态试验数据修正了发动机各部件及组合结构有限元模型,确保了有限元模型的合理性。由计算所得发动机结构表面的振动速度值和试验值变化趋势一致,在部分频率段吻合较好。基于表面振动速度法通过Matlab编程获得了各部件的声功率级及其排序,能够有效地指导低噪声设计工作。通过有限元和边界元方法分别对不同激励工况下发动机结构振动响应和声学响应进行了预测,通过分析可知,在低频段范围内活塞激励和燃烧激励相对阀系激励对整机辐射噪声的影响大,高频段辐射噪声主要集中在1 700Hz左右频段,其中,阀系激励对该频段范围内辐射噪声的影响较大。

Characteristics of Structural Vibration and Radiated Noise for Diesel Engine

Based on the multi-body dynamics,finite element method(FEM) and boundary element method(BEM),the numerical prediction and analysis of structural vibration and radiated noise for diesel engine were studied systematically.The finite element models of engine components and composite structure were corrected with the modal test data,which ensured the validity of model.The calculated vibration velocity values of engine structural surface were in good agreement with the experimental data in the whole trend and in some frequency bands.Based on the surface vibration velocity method,the sound power level value and sorting were acquired through Matlab programming,which could guide the low-noise design effectively.The engine structure vibration and acoustic responses were further predicted with the FEM and BEM.The result shows that the piston and combustion excites have more influences than the valve train excites on radiated noises in low frequency band.The high frequency noise mainly concentrates in the frequency band of around 1 700 Hz,which is influenced more by the valve train.