高速涡轮轴系稳定性分析与实验研究

发布时间：2018-05-08 02:02

本文选题：稳定性 + 气膜振荡　；参考：《中国科学院研究生院（工程热物理研究所）》2014年博士论文

【摘要】：气体轴承支承的高速涡轮轴系具有结构紧凑、轴承功耗低、转速高、功率密度大等优点,广泛应用于空气制冷机、高速永磁电机、微型燃气轮机等高速微型动力设备中。高转速下轴承非线性气膜力引起的气膜振荡是影响轴承-转子系统稳定性的关键问题之一。本文重点开展气体轴承-转子系统稳定分析与实验研究,主要工作内容如下： 1.对气体轴承-转子系统稳定性进行定性分析。提出了包含旋转惯性项、轴颈涡动项、轴颈挤压项以及轴承供给压力项在内的有限长气膜力分析模型,以轴颈偏心率为函数给出工程稳定性判别准则及其推论,当ε≤εmax,且dε/dt≤0时,轴承-转子系统在工程上是可以稳定运行的；转子的偏心率在某转速点满足ε≤εmax,且偏心率对转速的导数小于0(即dε/dω≤0),作为转子继续升速的判据。并根据工程稳定性判别准则,从设计阶段和在线调整阶段,给出了提高轴承-转子系统稳定性的措施和方法。 2.提出了基于图谱分析的转子非线性振动行为分析方法。以气膜振荡起始点为界,选用不同的图谱来分析气膜振荡前后的动力学特征,给出了气膜振荡发生前不平衡量引起同频涡动的分析图谱和气膜振荡发生后气膜非线性引起低频涡动与振荡的分析图谱,并在实验中验证了非线性振动行为分析方法的有效性和合理性。 3.搭建高速气体轴承-转子系统实验台。完成动力单元、实验台本体、振动测试单元以及远程监控单元的设计与搭建工作,其轴系设计转速在60000rpm；实验台能够呈现气膜涡动与振荡等非线性振动现象,实现了轴承气参数可控、可测量,转子的振动数据可在线监测、离线存储与分析,并实现实验现场的远程监控。 4.开展气膜约束状态下转子模态实验分析。制定模态实验方案,从激励的选取,测点布置方案的选取,激励与响应信号特征分析以及频响函数估计与评价几个方面论述模态实验过程,实验结果表明：设计转速内,转子平动、锥动、一阶弯曲固有频率随供气压力的增加而增加,且设计转速避开转子一阶弯曲和二阶弯曲临界转速值在合理裕度以上。模态实验结果为轴系升降速实验控制方案的制定,以及后续低频振动特性分析,提供基础性数据支撑。 5.开展转速、轴承供气压力、金属橡胶对轴承-转子系统稳定性影响的实验研究。采用非线性振动行为分析方法,重点分析分岔点、分岔点前和分岔点后转子动力学行为特征,结果表明：随着转速的增加,气体轴承-转子系统发生气膜振荡,发生气膜振荡的工频转速在两倍于平动临界转速以上；合理的轴承供气压力能够推迟分岔点,即气膜振荡的起始点,进而提高轴系稳定运行的裕度；金属橡胶垫能够起到进一步推迟气膜振荡起始点的作用,同时降低轴系平动、锥动、一阶弯曲临界转速值及相应的振动幅值,提高轴系稳定性。 6.将稳定调整措施在气体轴承支承的高速微型动力设备中进行工程应用验证。实验结果验证了基于图谱分析的非线性振动行为分析方法以及工程稳定判别准则的合理性和实用性。
[Abstract]:The high speed turbine shaft bearing supported by gas bearing has the advantages of compact structure, low bearing power, high speed and high power density. It is widely used in high speed micro power equipment, such as air chiller, high speed permanent magnet motor, micro gas turbine and so on. The air film oscillation caused by the nonlinear gas film force of bearing at high speed is the stability of bearing rotor system stability. One of the key problems of this paper is the stability analysis and experimental research of gas bearing rotor system. The main contents are as follows:
1. the stability of the rotor bearing rotor system is qualitatively analyzed. A finite length gas film force analysis model including the rotating inertia item, the journal journal vortex term, the axial neck extrusion term and the bearing pressure term is presented. The criterion for the stability of the engineering stability and its inference is given by the eccentric ratio of the journal. When the epsilon < max, and D E /dt < 0, the bearing - The rotor system can operate stably in engineering, the eccentricity of the rotor is satisfied at an epsilon of less than max at a rotational speed point, and the derivative of the eccentricity is less than 0 (d e /d Omega < 0), which is the criterion for the rotor to continue to rise. And the bearing rotor system is raised from the design stage and the on-line adjustment stage according to the criterion of the stability of the engineering. Measures and methods for stability.
2. the analysis method of nonlinear vibration behavior of rotor based on the map analysis is proposed. Taking the starting point of the gas film oscillation as the boundary, different atlas are used to analyze the dynamic characteristics before and after the air film oscillation, and the analysis Atlas of the same frequency eddy caused by the unbalance of the film before the occurrence of the gas film oscillation and the low-frequency eddy caused by the film nonlinearity after the gas film oscillation occurred after the gas film oscillation occurred. The dynamic and oscillatory analysis atlas, and verify the validity and rationality of the nonlinear vibration behavior analysis method in the experiment.
3. build a high speed gas bearing rotor system experiment platform, complete the design and construction of the dynamic unit, the experiment platform body, the vibration test unit and the remote monitoring unit. The axis design speed is 60000rpm, the experimental platform can present the nonlinear vibration of the air film vortex and oscillation and so on. The bearing gas parameters can be controlled, measurable and rotating. The vibration data of the child can be monitored online, offline stored and analyzed, and the remote monitoring of the experimental site can be realized.
4. the modal experiment analysis of the rotor under the condition of gas film constraint is carried out. The modal experiment scheme is formulated. The experimental process is discussed from several aspects: the selection of the excitation, the selection of the layout scheme of the measurement point, the characteristic analysis of the excitation and response signal and the estimation and evaluation of the frequency response function. The experimental results show that the rotor is moving, coning, and first order bending within the design speed. The natural frequency increases with the increase of gas supply pressure, and the design speed avoids the first order bending of the rotor and the two order bending critical speed above the reasonable margin. The experimental results of the modal experiment provide the basic data support for the formulation of the experimental control scheme of the shaft system and the following low frequency vibration characteristics.
5. to carry out the experimental study on the influence of the rotating speed, bearing pressure and metal rubber on the stability of the bearing rotor system. The nonlinear vibration behavior analysis method is used to analyze the bifurcation point, the bifurcation point and the dynamic behavior of the rotor after the bifurcation point. The results show that the gas bearing rotor system has gas film oscillation with the increase of the speed. The frequency speed of the gas film oscillation is more than two times that of the translation critical speed, and the reasonable bearing pressure of the bearing can postpone the bifurcation point, that is, the starting point of the gas film oscillation, and then improve the margin of the stable operation of the shaft system; the metal rubber pad can play a further role in postponing the starting point of the air film oscillation, and reduce the axis translation and cone movement. The critical speed and the corresponding vibration amplitude of the step can improve the stability of the shafting.
6. the stability adjustment measures are used to verify the engineering application of the high speed micro power equipment supported by gas bearings. The experimental results verify the rationality and practicability of the nonlinear vibration behavior analysis method based on the map analysis and the stability criterion of the engineering.

【学位授予单位】：中国科学院研究生院（工程热物理研究所）
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH113.25;TH133.3

【参考文献】