高速涡轮增压器轴承-转子系统不平衡响应及稳定性分析  

Unbalance Response and Stability Analysis of a High-Speed Turbocharger Bearing-Rotor System

作　　者：张毅 王伟 魏道高 王刚 许吉敏 刘焜 ZHANG Yi;WANG Wei;WEI Daogao;WANG Gang;XU Jiming;LIU Kun(Institute of Tribology,School of Mechanical Engineering,Hefei University of Technology,Anhui Hefei230009,China;School of Automotive and Traffic Engineering,Hefei University of Technology,Auhui Hefei 230009,China)

机构地区：[1]合肥工业大学机械工程学院摩擦学研究所,安徽合肥230009 [2]合肥工业大学汽车与交通工程学院,安徽合肥230009

出　　处：《摩擦学学报》2022年第3期620-631,共12页Tribology

基　　金：国家自然科学基金(51875154,51805131,51875152);安徽省重点研究与开发计划(202004a05020057)项目资助。

摘　　要：汽车涡轮增压器广泛采用浮环轴承支承的小型轻质转子系统,以实现100000~300000 r/min的工作转速,提高发动机功率和动力性能,并降低燃油消耗和排放.在此超高速工况下,动压油膜的强非线性作用和转子固有的不平衡效应使该系统呈现出复杂的动力学现象,其中油膜涡动、振荡、跳跃、倍周期分岔和混沌等非线性动力学行为对增压器的健康运转意义重大,因而备受关注.本文作者从摩擦学动力学耦合的角度出发,基于流体动压轴承润滑理论和有限差分法计算非稳态油膜压力,结合达朗贝尔原理和传递矩阵法建立了转子离散化动力学方程,提出了一种由双油膜浮环支承的涡轮增压器转子系统动力学模型,并从转子轨迹、轴承偏心率、频谱响应、庞加莱映射和分岔特性等方面比较分析,描述了该非线性轴承-转子系统的不平衡效应及油膜失稳特征.结果表明:转子一般在相对低速下作稳定的单周期不平衡振动,在高转速下其被油膜失稳引起的次同步涡动所抑制,但不平衡量的增加可阻碍转子以拟周期运动通向混沌运动的路径;适当不平衡补偿下,由于内、外油膜间交互的非线性刚度和阻尼作用,在油膜失稳区间之间的中高速区会出现适合增压器健康运转的稳定区间.In the field of diesel,petrol and aero engines design,exhaust gas turbocharging has become a critical technique for enhancing its air intake and power while reducing fuel consumption and emissions.The core component in a turbocharger is the rotor-bearing system at ultra-high speed.The rotor of small size and light weight supported by floating-ring bearing(FRB)has been extensively used in automotive turbocharger to reach the speeds between 100000and 300000 r/min,but complicated nonlinear dynamics phenomena including oil whirl/whip,jumping,bifurcation and chaos probably appear in the response of unsteady fluid-film force and self-excited unbalance force,which have a great significance for the healthy operation of the high-speed turbocharger.By applying the finite difference method to calculate the transient pressure distribution of double fluid film based on Reynolds lubrication theory,this paper developed a nonlinear oil-film force model for the floating-ring bearing through Simpson integration.On this foundation,D’Alembert’s principle and the transfer matrix method were adopted to establish the dynamical differential equations for the turbocharger rotor considering the gyroscopic effect induced by impellers.Consequently,this work described a coupling model of dynamics and tribology for the turbocharger bearing-rotor system.The numerical methods in nonlinear dynamics,e.g.phase portrait,Poincare mapping,bifurcation diagram and frequency-response spectrum,were then adopted to analyze the rotor unbalance vibration response and bearing oil-film instability characteristics of this system,providing theoretical support for the design of turbocharger bearing-rotor.The results showed that at a small impeller unbalance(unbalance offset distance e=4μm),the 0.49×/0.13×sub-synchronous inner/outer oil whirl suppresses the 1×synchronous unbalance effect and the system was unstable throughout a wide range of ascending rotor speeds.While the unbalance was relatively large(e=14μm),the generated 1×synchronous unbalance vib

关 键 词：涡轮增压器转子 浮环轴承 非线性振动 油膜涡动/振荡 稳定性 

分 类 号：TH117.2[机械工程—机械设计及理论]