【作者】 赵永辉；

【导师】 于慎波；

【作者基本信息】 沈阳工业大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 离心式压缩机的稳定性取决于转子-轴承系统本身的特性，本文针对离心式压缩机转子-轴承系统临界转速的计算进行研究，主要研究范围是：1．计算叶轮的转动惯量；2．计算可倾瓦径向滑动轴承的动力系数；3．计算转子-轴承系统的临界转速。 叶轮转动惯量的计算采用解析与离散相结合的方法，轮盘与轮盖采用解析法进行求解，而叶片则采用离散的方法，这样既可以保证计算的精度，又可以提高计算的速度。 可倾瓦径向滑动轴承动力系数的计算是以雷诺方程为基础，首先对瓦块表面进行网格划分，采用差分和SOR方法解出各瓦块在静态平衡位置时各点的压力分布，并进一步解出各瓦块在静平衡状态时的动力系数；然后再采用间接法换算出各瓦块在摆动时的动力系数。间接法可以减少求解雷诺方程的次数，加快了求解速度，也减少了由于多次运用差分法造成的误差。 转子-轴承系统临界转速的计算采用传递矩阵法，由于引入了可倾瓦径向滑动轴承，因此，这是一个有阻尼的系统，这个系统的状态向量含有8个元素，系统特征方程的阶数为8n阶，以40个节点的系统为例，特征方程的阶数就将达到了320阶，而且特征方程的系数差别巨大，求解这个方程最大的难点就是如何避免丢根。本文采用QR法对特征方程进行求解，从而彻底避免了丢根的危险。更多还原

【Abstract】 Stability of centrifugal compressor depends on rotor-bearing system properties. This paper focus on critical speed calculation of rotor-bearing system of centrifugal compressor. The content of this paper including: 1 Moment of inertia calculation of impeller; 2 Stiffness and damping coefficients calculation of tilting pad journal bearing; 3 Critical speed calculation of rotor-bearing system.Both analytic and discrete methods are applied to calculation of impeller moment of inertia. Analytic method is used for cover and hub calculation; discrete method is used for blades calculation. In this way, not only can the result accuracy be guaranteed, but also calculating speed be improved.Tilting pad journal bearing stiffness and damping coefficients calculation is based on Reynolds equation. First, meshing on the pad surface, and working out static pressure distribution of each pad by both finite differences and SOR methods. Second, calculating stiffness and damping coefficients of each pad when it is balanced. Finally, calculating stiffness and damping coefficients of each pad when it is swing by indirect method. Indirect method can reduce Reynolds equation calculating times, expediting calculation speed and reducing error caused by finite differences.Transfer matrix method will be used to calculate critical speed of rotor-bearing system in this paper. Because applying tilting pad journal bearing to rotor, this is a system with damping. As there are eight elements for each state vector, the order of characteristic polynomial is 8n. For example, a system with 40 lumped masses, its order of characteristic polynomial will reach 320. Further more, because there are huge differences between the coefficients of characteristic polynomial, the difficulty of solving this polynomial equation is how to avoid root missing. QR更多还原