船舶艉轴承间隙对轴系回旋振动特性影响分析

Influence of stern bearing clearance on the lateral vibration characteristics of a ship′s shafting system

为了探究船舶艉轴承的支承刚度对推进轴系回旋振动特性的影响,本文利用流体动力润滑理论,通过求解适用于径向轴承的Reynolds方程,分析了轴承液膜刚度的动态特性,进而利用有限元方法分析其对轴系回旋振动的影响。研究发现液膜刚度随轴颈转速增大呈非线性变化,在特定转速下会发生波动。轴承设计间隙增大会导致水平方向的刚度增大,而竖直方向的刚度会先减后增。通过ANSYS有限元软件建立了船舶推进轴系模型,分析艉轴承不同设计间隙对轴系回旋振动的影响。当临界转速处于刚度出现波动的转速范围内时,发生耦合作用使固有频率产生影响,为船舶轴承设计间隙选取提供理论依据。

To explore the influence of the support stiffness of the ship stern bearing on the lateral vibration characteristics of the propulsion shafting,this paper uses the hydrodynamic lubrication theory to solve the dynamic characteristics of the bearing liquid film stiffness by solving the Reynolds equation for radial bearings,and then the influence on the lateral vibration characteristics of the shafting is analyzed using the finite element method.The liquid film stiffness changes nonlinearly with the increase in journal speed and fluctuates at a specific speed.An increase in the bearing design clearance increases the stiffness in the horizontal direction while decreasing and then increasing the stiffness in the vertical direction.The ship propulsion shafting model is established using the finite element software ANSYS,and the influence of different design clearances of the stern bearing on the lateral vibration of the shafting is analyzed.When the critical speed is within the range at which the stiffness fluctuates,the coupling effect occurs and affects the natural frequency.This study provides a theoretical basis for selecting the design clearance of ship bearings.