船用低速柴油机曲轴轴向振动研究

Study on the Axial Vibration of the crankshaft on Marine Low-Speed Diesel Engine

以船用大功率低速柴油机柔性体曲轴为对象,在考虑气体力、运动部件惯性力、扭纵耦合效应等因素的情况下,建立曲轴、连杆、活塞的刚柔混合动力学模型。通过数值仿真,分别对连杆推力、连杆法向力和切向力对曲轴轴向振动的影响进行分析。分析结果表明:法向力直接引起曲轴纵振,切向力首先引起曲轴扭振,进而引起曲轴纵振;同时,法向力和切向力对曲轴轴向振动的影响非常相近;而连杆推力(法向力和切向力合力)引起的曲轴轴向振动是扭纵耦合振动的结果,并非两种分力作用结果的简单叠加。

The rigid-flexible mixed model for the cranktrain system of the marine low-speed diesel engine is established considering the gas force, the inertia moment of moving parts and the coupling effect between torsional and axial vibration. The result of numerical simulation shows that the normal force on the crankpin is the directly exciting factor to the crankshaft axial vibration, but the tangent force is the indirectly exciting factor. Besides, the normal force and tangent force have similar influence on the axial vibration. Moreover, the axial vibration caused by the push force of con-rod is the result of torsional coupled axial vibration.