| In the process industry,centrifugal compressors are one of the core units of production operations,and their function is mainly to complete the pressurization and transport of process gases and to connect the entire production process.Gear speed increasing centrifugal compressor,because of its high compression efficiency,large compression flow and small size,is increasingly used in process gas compression,but the abnormal vibration and operating state of the gearbox will directly affect the stable operation of the compressor unitIn this paper,taking the compressor unit in service of a factory as the research object,the vibration characteristics of single rotor inside the gearbox and its coupling characteristics are studied according to the theory of rotordynamics.The main work is as follows:(1)The solid three-dimensional modeling of the internal rotation system of the gearbox was completed by using Solidworks software,and the vibration characteristics of the high and low speed single-shaft and rotor coupling system inside the gearbox were analyzed with the help of finite element analysis software,and the modal state and critical speed of the rotor were solved.The analysis of the 15thorder mode shape before the rotor shows that the dominant vibration form of the low-speed shaft and high-speed shaft rotor is lateral vibration.The comparative analysis of Campbell plot shows that compared with the single-rotor modal frequency,the modal frequency of the coupled rotor system is less affected by the rotational speed.The modal and critical speeds of the coupling rotor system include part of the modal and critical speeds of the single axis,and derive new modes and critical speeds.With the increase of bearing stiffness and gear contact friction coefficient,the modal frequency of each stage of gear-coupled rotor system shows an upward trend.(2)Through the harmonic response analysis module of finite element analysis software,the influence of single rotor mass imbalance on the rotation process is simulated.The mass unbalance is loaded at different node positions of the low-speed shaft and the high-speed shaft in turn,and the amplitudefrequency response curves of the three node positions of the low-speed shaft and the high-speed axis are obtained.The low-speed shaft study shows that the loading position of the mass unbalance is changed,the number of spikes in the amplitude-frequency response curve of each node is unchanged,the shafting response of node A2 position is sensitive at 188Hz,the shafting response of node A3 position is sensitive at 486-488Hz,and the axial system response of node A1 position is sensitive at 1262-1268Hz.The highspeed shaft study shows that when there is mass imbalance in the left and right bearing positions of the high-speed shaft rotor,the vibration amplitude of the unbalanced response of the left and right bearing positions is greater than that of the other two positions.The response relationship between the size of the unbalanced mass and the size of the mass eccentricity on each node was studied,and it was found that the change trend of the amplitude-frequency response graph was basically the same,and with the increase of the unbalanced mass or mass eccentricity,the peak value also showed an upward trend.(3)Through transient dynamics solution analysis,the influence of radial load on the operating state of high and low speed rotor is studied,and the analysis of the axial trajectory diagram shows that when the peak of the radial load gradually increases,the greater the amplitude of the vibration of the low-speed shaft axis in the X direction,the longer the time required to stabilize the quasi-periodic circular motion.The high-speed axis study shows that with the gradual increase of the loading force,there is a large vibration in the negative direction of the axis X at the beginning of the axis,and eventually maintains the quasi-periodic circular motion,and the amplitude of the vibration in the positive and negative direction of the X axis after it tends to stabilize. |
PDF Full Text Request