| The dynamic characteristics of rotor system include critical speed calculation,modal mode analysis,harmonic response characteristics,etc.it is not only related to the structure of the rotor itself,but also closely related to the supporting characteristics of the bearing on the shaft and the structure of the sealing system,and the dynamic characteristics of the system provide feedback guidance for the dynamic analysis and structural design of the sealing.Therefore,according to the specific rotor system of finger seal,the time-varying sealing force model is established according to the working principle of finger seal.The characteristics of the seal force are analyzed.The function of the rolling bearing support and finger seal structure on the shaft is considered.The modal harmonious response characteristics of the finger seal rotor bearing system are analyzed.The influence of the relevant parameters on the dynamic characteristics of the rotor system is studied,which provides an important theoretical reference for the dynamic characteristics analysis and the dynamic design of the seal structure.The main contents and conclusions are as follows:1.Establish a dynamic equation based on the physical model of the rotor system,ignore the damping of the rolling bearing,and equate it as an elastic support with a certain stiffness,and the support stiffness of cylindrical roller bearing and angular contact bearing is determined.The dynamic equation is solved by Simulink state space module,the radial runout of the rotor is obtained,and the influence law of the speed on the runout of the rotor is analyzed.The results show that when the rotor speed is 40000r/min,the maximum radial displacement at the centroid of the rotor is 7.267 × 10-3mm,and the maximum radial displacement of the rotor at the sealed track is 0.02665mm.And as the rotation speed increases,the rotor displacement response amplitude gradually decreases,and finally gradually stabilizes.2.According to the working principle and structural characteristics of finger seal,the time-varying model of finger beam sealing force in contact area is established.The time-varying sealing force of finger blade is solved by coordinate transformation,and the influence of finger seal structural parameters and actual working conditions on sealing force is analyzed.The results show that:in the global coordinate system XOY,the time-varying sealing force in the X and Y directions all show periodic changes,and the single-layer fingertip sealing force amplitude is 25.66N.For the multi-layer fingertips,the odd-numbered fingertips have the same sealing force,the even-numbered fingertips have the same sealing force,and the time-varying sealing force amplitude of the three-layered fingertips is 56.59N.In addition,with the increase of finger beam number,seal layer number,rotor radial runout and speed,the amplitude of time-varying sealing force will increase.The rotor speed will also affect the period of time-varying sealing force.With the increase of speed,the period will shorten.3.The critical speed of the rotor system is solved by the transfer matrix method and the finite element method,and the influence of rolling bearing stiffness and finger seal structure stiffness on the modal characteristics of the rotor system is analyzed by ANSYS Workbench.The results show that the relative errors of the two methods are less than 4%;the stiffness of position 1 cylindrical roller bearing mainly affects the first-order critical speed of the shaft,the stiffness of position 2 angular contact bearing mainly affects the second-order and third-order critical speed,and the stiffness of position 3 angular contact ball bearing mainly affects the third-order critical speed of the shaft;With the increase of seal stiffness,the first critical speed increases,and the corresponding shaft deformation decreases.The highest speed of a specific rotor system with finger seal is between the first and second critical speeds.Therefore,the first and second critical speeds of the rotor system can be improved by increasing the structural stiffness of finger seal and the stiffness of bearings 1 and 2.4.Considering the role of rolling bearings and finger seals,according to the established finite element model,the harmonic response analysis of the rotor system is carried out through ANSYS Workbench.The results show that with the increase of bearing stiffness,the displacement response amplitude of the rotor system decreases;with the increase of the sealing force,the displacement response amplitude of the rotor system at the first and second order critical speeds decreases.The displacement response amplitude increases;the number of seals has a relatively obvious influence on the displacement response of the rotor system under the second and third orders;in addition,the displacement response amplitude of the rotor system under the first and third orders in this paper is mainly affected by the position a seal,And the second-order displacement response amplitude is mainly affected by the position c seal.In actual engineering,the rotor system should be designed reasonably in consideration of the structure,quantity and position of the finger seal. |
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