基于CFD球面动静压气体轴承气膜动态稳定性研究

发布时间：2018-11-13 16:03

【摘要】：随着高速旋转机械以及精密仪器的快速发展,气体润滑轴承以其特有的特点正在逐渐被人们所认知并重视。与传统的润滑轴承相比,气体润滑轴承的优点非常明显,主要表现为运转噪声小、摩擦损耗小、几乎不产生热量、低振动、寿命长、能够在特殊工况下稳定工作等。动静压混合气体轴承综合了动压轴承与静压轴承的优点,即在转子启停阶段采用静压气体轴承的供气方式,从而避免了轴承转子与定子之间的固体接触,而轴承在高速旋转时停止外界供气,利用动压效应进行承载,这大大减小了功耗。由于动静压气体轴承最高转速每分钟可达几十万转,所以轴承气膜特性的变化规律具有非常复杂的非线性且随机的特点,而轴承的气膜特性直接影响轴承转子的运动状态,因此对轴承气膜承载性能和动态特性的研究是研究轴承动态特性及稳定性的关键。本文以球面螺旋槽动静压气体轴承为研究对象,应用PROE软件中的球面坐标系的方法,建立了球面螺旋槽动静压气体轴承的三维气膜模型,并以CFD技术为基础,将三维气膜模型处理成润滑分析有限元模型,借助FLUENT软件,对球面螺旋槽气体动静压轴承的静态特性以及动态特性进行仿真分析,揭示轴承的结构参数(槽宽比、槽深比、螺旋角、槽数)对轴承气膜压力分布以及承载能力的影响规律,并以此为依据,对轴承的结构参数进行了初步优化。在稳态计算的基础上,应用FLUENT软件中的6 DOF被动型网格计算模块,对球面螺旋槽动静压气体轴承在动态运转中的失稳过程进行模拟分析,通过研究轴承在瞬态运动过程中的轴心轨迹图、频谱图,揭示了轴承从稳定运转到失稳的各种运动状态的变化规律,选择轴承在不同运动状态下,特殊点的速度、力和位移的变化量,计算出轴承在此时的刚度、阻尼系数,以此建立轴承的运动状态与刚度、阻尼系数之间的联系,并以刚度、阻尼系数为目标,对轴承的结构参数进行进一步优化。
[Abstract]:With the rapid development of high speed rotating machinery and precision instruments, gas lubricated bearings are gradually recognized and valued for their special characteristics. Compared with the traditional lubricated bearings, the gas lubricated bearings have many advantages, such as less noise, less friction loss, little heat, low vibration, long life, and can work stably under special working conditions. The hybrid gas bearing combines the advantages of the hydrodynamic bearing and the hydrostatic bearing, that is, the air supply mode of the hydrostatic gas bearing is adopted in the starting and stopping stage of the rotor, thus avoiding the solid contact between the rotor and the stator of the bearing. The bearing stops the external gas supply when rotating at high speed and uses the dynamic pressure effect to carry on the load, which greatly reduces the power consumption. Because the maximum rotational speed of the static and static gas bearing can reach several hundred thousand revolutions per minute, the variation law of the film characteristic of the bearing has very complicated nonlinear and random characteristics, and the film characteristic of the bearing directly affects the motion state of the bearing rotor. Therefore, the study of bearing film bearing performance and dynamic characteristics is the key to study bearing dynamic characteristics and stability. In this paper, the three-dimensional gas film model of spherical spiral groove static and static gas bearing is established by using the method of spherical coordinate system in PROE software, and based on CFD technology, the spherical spiral groove static and static gas bearing is taken as the research object. The three-dimensional gas film model is treated as the finite element model of lubrication analysis. The static and dynamic characteristics of the spherical helical groove gas static and static bearing are simulated and analyzed with the help of FLUENT software, and the structural parameters of the bearing (groove width ratio, slot depth ratio) are revealed. The influence of spiral angle and slot number on the film pressure distribution and bearing capacity of bearing was studied and the structural parameters of bearing were preliminarily optimized. On the basis of steady state calculation, using 6 DOF passive mesh calculation module in FLUENT software, the instability process of spherical spiral groove static and static gas bearing in dynamic operation is simulated and analyzed. By studying the track diagram and spectrum diagram of the axis center in the transient motion process of the bearing, this paper reveals the changing law of the various motion states of the bearing from stable to unstable, and selects the speed of the special point of the bearing in the different motion state. By calculating the stiffness and damping coefficient of the bearing at this time, the relation between the motion state of the bearing and the stiffness and damping coefficient is established, and the stiffness and damping coefficient are taken as the target. The structural parameters of the bearing are further optimized.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH133.36

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