基于流固耦合的离心压缩机轴系振动特性分析

Analysis of Vibration Characteristic of Centrifugal Compressor Shafting Based on Fluid-structure Coupling

为探究滑动轴承结构参数对离心压缩机轴系振动特性的影响规律,以某型离心压缩机轴承-转子系统为研究对象,首先采用多参考系模型、mixture两相流模型、liner层流模型以及UDF程序,利用隐式耦合求解法对考虑黏温特性的滑动轴承油膜流场进行求解,得到油膜流场压力分布进而对转子系统进行了单向稳态流固耦合分析,探究了轴承间隙比、宽径比对轴系振动特性的影响规律。结果表明:(1)油膜压力随轴承间隙比的增大而减小;临界转速随轴承间隙比的增大而小幅度减小,最大降幅为0.89%;轴系稳定性随间隙比增大呈现先减后增的变化趋势,研究轴系在间隙比为0.0014处稳定性最好。(2)油膜压力随轴承宽径比的增大而增大;临界转速随轴承宽径比的增大而增大,最大增幅为6.9%;轴系稳定性并未随轴承宽径比的增大而呈现规律性变化,研究轴系在宽径比为0.8处稳定性最佳。因此,轴承结构参数对轴系振动特性的影响并非是完全规律性的,我们需要根据旋转机械的实际工况选择合适的轴承结构参数。

In order to explore the influence law of structure parameters of sliding bearings on vibration characteristics of centrifugal compressor shafting,this paper takes the bearing-rotor system of a certain type of centrifugal compressor as the research object.Firstly,a multi-reference system model,mixture two-phase flow model,liner laminar flow model and UDF program are adopted.The implicit coupling method was used to solve the oil film flow field of the sliding bearing considering the viscosity and temperature characteristics,and the pressure distribution of the oil film flow field was obtained.Then the unidirectional steady-state fluid-structure coupling analysis was carried out on the rotor subsystem,and the influence law of the bearing clearance ratio and the width-diameter ratio on the vibration characteristics of shafting was explored.The results show that the oil film pressure decreases with the increase of the bearing clearance ratio,the critical speed decreases slightly with the increase of bearing clearance ratio,and the maximum decrease is 0.89%.The stability of shafting decreases first and then increases with the increase of clearance ratio.The stability of shafting studied in this paper is the best when the clearance ratio is 0.0014.The results also show that the oil film pressure increases with the increase of the bearing clearance ratio,the critical speed increases with the increase of the bearing width-diameter ratio,and the maximum increase is 6.9%.Shafting stability does not change regularly with the increase of bearing width to diameter ratio.The shafting studied in this paper has the best stability when the width to diameter ratio is 0.8.Therefore,the influence of bearing structural parameters on the vibration characteristics of shafting is not completely regularly,the appropriate bearing structural parameters should be chosen according to the actual working conditions of rotating machinery.