采用箔片轴承的高速透平转子动力学分析

Dynamic Analysis of High Speed Turbine Rotor with Foil Bearing

为研究采用箔片轴承的转子轴承系统的动力学特性,以高速透平膨胀机的轴承转子系统作为研究对象,建立有限元转子动力学模型,得到转子系统对应的临界转速大小,并计算轴承支撑刚度对转子系统临界转速的影响,揭示高速透平膨胀机转子涡动频率随转速的变化规律,获得轴承刚度、阻尼特性对轴承稳定性的影响。同时,为了更加准确地描述转子的运动状态,对转子系统进行时域分析,得到转子轴心轨迹和相应的频谱分析,并将时域分析结果与实验测试结果相对比,发现两者吻合良好。数值计算结果表明:箔片轴承的良好的刚度、阻尼特性使高速透平转子系统具有较宽的工作转速和更好的稳定性;对于转子系统的时域分析可以更加直观准确地描述转子的运动状态。

In order to study the dynamic characteristics of the rotor bearing system with gas foil bearings,the classical finite element rotor dynamics models were set up based on the rotor system of the high speed turbo expander.The corresponding critical speed of the rotor system was obtained and the influence of bearing stiffness on the critical speed of the rotor system was analyzed through the numerical calculation model.The rotor swirl frequency with the change of speed was revealed,and the influence of bearing stiffness and damping characteristics on stability of bearing was discussed.In order to describe the motion state of the rotor more accurately,the time-domain analysis of the rotor system was carried out,and the orbit of rotor center and the corresponding frequency analysis was obtained,it was found that the results of time-domain analysis matched well with the experiment results.The results show that the wide operating speed range and better stability are obtained in the high speed turbo expander due to the excellent stiffness and damping characteristics of foil gas bearings,and the motion state of the rotor is described more accurately by applying time-domain analysis,which is verified by the numeral calculations.