基于3D瞬态流场计算的滑动轴承非线性油膜力分析

Analysis of nonlinear oil film force of journal bearings based on 3D transient flow field calculation

滑动轴承非线性油膜力的计算结果直接决定了转子-轴承系统非线性动力学分析的精度和效率。针对轴颈扰动下滑动轴承瞬态流场计算中的网格畸变问题,提出了一种适用于小间隙流场3D瞬态计算的变流域动网格技术。通过对滑动轴承润滑流场的瞬态计算,对不同扰动下的线性油膜力与瞬态油膜力进行了对比,并在考虑油膜非线性的影响下,分析了瞬态油膜力径向和切向分量的变化过程。结果表明:大扰动工况下,滑动轴承的动特性分析有必要计入油膜非线性的影响;进油口和油槽的存在会明显降低径向油膜力,导致油膜支撑刚度降低;瞬态油膜力切向分量的减小导致了滑动轴承阻尼的降低,进而引起油膜失稳。

The result of the nonlinear oil film force analysis of journal bearings directly determines the accuracy and efficiency of the nonlinear dynamic analysis of the rotor bearing system.According to the transient analysis of nonlinear oil film force of journal bearings under large disturbance,this paper proposes a dynamic mesh method of structure grids suitable for 3D transient flow field calculation.The linear and nonlinear oil film forces under different disturbance were compared.Under the influence of oil film nonlinearity,the radial and tangential components of transient oil film force were analyzed.It was observed that the disturbance impact was necessary to be taken into consideration in the analysis of nonlinear oil film force;the oil inlet and the oil tank will significantly reduce the radial oil film force,causing the support stiffness reduction.The decrease of the tangential component of transient oil film force causes the reduction of journal bearing damping,thereby causing oil film instability.