基于油膜力做功的滑动轴承动力特性及转子稳定性

Dynamic characteristics of journal bearing and stability of rotor system based on work of oil film force

应用滑动轴承两相流理论和非定常动网格技术,建立了基于两相流理论的滑动轴承动力特性多频椭圆涡动求解模型,在验证求解模型准确性的基础上,研究了滑动轴承单相流与两相流模型的油膜压力分布特点以及轴颈多频椭圆涡动轨迹下油膜力的变化规律,并基于油膜力做功的方法定量分析了轴颈涡动频率、偏心率对转子稳定性的影响.研究结果表明:建立的转子多频涡动模型,只要2次非定常求解便可得到多个涡动频率下的动力特性系数,提高了分析效率;轴颈涡动引起油膜力随之变化,且油膜力的频率与轴颈涡动频率相同;轴颈涡动频率对滑动轴承动力特性系数和转子稳定性影响较大,需要考虑轴颈涡动频率对滑动轴承动力特性的影响;轴颈偏心率越大,油膜力对轴颈所做负功的绝对值越大,轴颈涡动能量被消耗得越快,越有利于转子的稳定性.

The stiffness and damping coefficients of journal bearing are important parameters that affect the dynamic characteristics of rotor system.The multiple-frequency elliptical orbits whirl model based on two-phase flow theory was established by the unsteady solution and mesh deformation method.On the basis of verifying the accuracy of solution model,oil film pressure distribution features of single-phase flow and two phase flow,the change of the oil film force in the whirl orbits of the journal,and the influence of the whirling frequencies and eccentricity ratio on the stability of rotor system were stu-died.The results show that only if two unsteady computations are needed,the rotordynamic coefficients of journal bearing can be obtained by the multiple-frequency elliptical orbits whirl model,which enhances analysis efficiency.Oil film force produced by the whirl motion changes with the variation of the whirl frequency of the journal,and the frequency of the oil film force is the same as that of the whirl motion of the journal.It is necessary to consider the whirl frequency when the rotordynamic characteristics and the stability of journal bearing are studied.The larger the eccentricity ratio of the journal,the greater the absolute value of the negative work of the oil film force,the faster the rotor whirling energy is consumed,the better the rotor stability.