高速气体轴承结构性能分析与实验研究

发布时间：2018-01-15 03:03

本文关键词：高速气体轴承结构性能分析与实验研究　出处：《中国科学院研究生院(工程热物理研究所)》2014年博士论文　论文类型：学位论文

【摘要】：气体轴承是采用粘度低且随温度变化小、清洁无污染、耐辐射、可压缩性好等特性的气体作为润滑介质的滑动轴承。气体的诸多特点一方面使轴承具有功耗低、寿命长和精度高等优点,在高速支承、低摩擦低功耗支承、高精度支承和特殊工况下的支承领域占有绝对的应用优势。另一方面,气体的低粘度和可压缩性等特点抑制了轴承在重载领域的应用。由于气体的可压缩性,气体轴承不能像液体轴承一样通过提高润滑介质压力来不断提高轴承承载力。研究发现,当不断增加气体供气压力时,气体在节流口流入轴承间隙处会发生拥塞,并在轴承间隙中出现亚音速流、超音速流甚至激波等复杂的流场特性,在超音速区域造成压力损失,降低了轴承的承载力。为了保证转子高速运转的可靠性和特殊工况下对重载的需求,轴承的稳定性和承载特性是关键。因此,本文针对气体轴承,研究了气膜流场特性、轴承承载特性以及轴承支承下转子运行的稳定性,主要开展了以下工作：1、对包括节流流道和轴承间隙内的完整轴承气流流场进行建模,根据轴承结构和润滑气体参数,确定轴承间隙气体选用的计算模型,对气体轴承静压流场进行分析。首先1)建立节流口流道模型,计算节流口出口气体参数,并判断节流口出口是否达到拥塞；2)根据润滑气体状态参数和轴承结构参数,判断轴承间隙内是否发生激波,确定轴承间隙气膜流态类型；3)分别选用亚音速和超音速模型来计算轴承间隙内流场特性。通过分析润滑气体状态参数、轴承结构参数和轴承间隙内流场分布的关系,来进行合理的静压气体轴承结构设计。2、从气体动力学方程、连续性方程及气体状态方程出发,推导可压缩气体雷诺方程。采用有限元法求解方程,使用伽辽金加权余量法离散方程,得到雷诺方程有限元方程形式。使用三角形单元作为插值函数,迭代法求解有限元方程,得到轴承压力分布。计算了气体静压轴承、人字槽型线动压轴承和动静压混合轴承的承载力、涡动力、刚度和阻尼。3、采用转子的动力学特性来衡量轴承特性的方法,建立轴承支承转子的有限元模型,求解了转子轴承系统固有频率和不平衡响应,并研究了轴承动力特性参数对轴承转子系统固有频率的及转子振幅的影响。4、对气体轴承静、动态特性两方面展开实验：1)静特性实验用来测试轴承的承载力和刚度；2)动特性实验在高速旋转的转子轴承设备上,采用非线性测试分析方法,测试不同结构气体轴承支承下转子高速下振动特性,通过转子的振动特性反应轴承的性能。实验研究静压轴承支承下出现的低频涡动、双低频振动和振荡现象；动压轴承不同槽型线对转子的影响；动静压混合轴承特性研究。
[Abstract]:Gas bearing is a sliding bearing with low viscosity and little change with temperature, clean and pollution-free, radiation resistant, good compressibility and other characteristics of the lubricating medium. On the one hand, the gas features make the bearing have low power consumption. The advantages of long life and high precision, such as high speed support, low friction and low power support, high precision support and support under special working conditions have absolute advantages. On the other hand. The low viscosity and compressibility of gas restrain the application of bearing in the field of heavy load. Because of the compressibility of gas. Gas bearings cannot increase bearing capacity by increasing lubricating medium pressure as liquid bearings do. The gas flows into the bearing clearance at the throttle port will be congested, and the subsonic flow, supersonic flow and even shock wave will appear in the bearing clearance, causing pressure loss in the supersonic region. The bearing capacity is reduced. In order to ensure the reliability of high-speed operation of the rotor and the demand for heavy load under special conditions, the bearing stability and bearing characteristics are the key. Therefore, this paper aims at the gas bearing. The characteristics of gas film flow field, bearing bearing characteristics and the stability of rotor under bearing support are studied, and the following work is mainly carried out. The gas flow field of the whole bearing including throttle passage and bearing clearance is modeled. According to the structure of bearing and the parameters of lubricating gas, the calculation model of gas selection for bearing clearance is determined. The static pressure flow field of gas bearing is analyzed. Firstly, the throttle channel model is established, the gas parameters of throttle outlet are calculated, and the congestion of throttle outlet is judged. 2) judging whether shock wave occurs in bearing clearance according to lubricating gas state parameter and bearing structure parameter, and determining the type of gas film flow state in bearing clearance; 3) the subsonic and supersonic models are used to calculate the characteristics of the flow field in the bearing clearance, and the relationship among the lubrication gas state parameters, the bearing structure parameters and the distribution of the flow field in the bearing clearance is analyzed. Based on the gas dynamics equation, continuity equation and gas state equation, the compressible gas Reynolds equation is derived, and the finite element method is used to solve the equation. The finite element equation of Reynolds equation is obtained by Galerkin weighted residual method, and the finite element equation is solved by iterative method using triangular element as interpolation function. The bearing pressure distribution is obtained. The bearing capacity, vortex force, stiffness and damping of the aerostatic bearing, the herringbone linear hydrodynamic bearing and the hybrid bearing are calculated. The finite element model of bearing supporting rotor is established by using the method of measuring bearing characteristic by rotor dynamic characteristics, and the natural frequency and unbalanced response of rotor bearing system are solved. The influence of bearing dynamic characteristic parameters on the natural frequency and rotor amplitude of bearing rotor system. The static characteristic experiment is used to measure bearing bearing capacity and stiffness. 2) the dynamic characteristics of the rotor bearing equipment with high speed rotation are tested by using the nonlinear test method to test the vibration characteristics of the rotor under the support of different structure gas bearings at high speed. The performance of the bearing is reflected by the vibration characteristics of the rotor. The phenomena of low frequency vortex, double low frequency vibration and oscillation under the support of the hydrostatic bearing are studied experimentally. The influence of different grooves of hydrodynamic bearing on rotor; Study on the characteristics of Hybrid bearing with static and static pressure.
【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】：TH133.3

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