Investigation Of Unbalanced Response Of Vertical Pump Rotor Supported By Roller Bearing And Annular Seal

With the improvement of the vibration requirements of rotating machinery,the coupling effect between different directions of the rotor,the influence of nonlinear support of rolling bearings and the fluid excitation on the vibration characteristics of rotor is becoming more prominent.Since the shaft frequency has a modulating effect on the high-frequency signal,the optimization of the shaft frequency is the key problem in the work of vibration and noise reduction,but the efficiency of high-precision field dynamic balance of rotating machinery under complex excitation conditions is generally low,which has become the main factor restricting the performance of vibration and sound stealth of the equipment.Therefore,it is of great significance to study and establish a rotor coupled vibration model in accord with actual working conditions,which has theoretical value and engineering significance for predicting dynamic characteristics of the rotor-bearing-sealing system and improvement of the high-precision field dynamic balance method.In this paper,the six-degree-of-freedom motion equation in consideration of the bending-tosion-axial coupling vabration is established.By combining the complex rolling bearing dynamic model including axial and bending supporting,the influences of various excitation and bearing parameters on the nonlinear vibration characteristics of rotor system are studied.The unbalanced response law of rotor under different operating conditions and structural parameters is aquired.The main contents are as follows:(1)The six-degree-of-freedom motion equation including the coupling between lateral bending,axial and torsion was constructed.On this basis,the influence analysis of speed,excitation force and shafting parameters on multi-directional coupling vibration characteristics was further analyzed.The results show that the influence of bending moment and torsional excitation on lateral and axial response is obvious,the response characteristics under radial excitation are closely related to the torsional natural frequency.(2)The five-degree-of-freedom dynamic model of ball bearings and cylindrical roller bearings in consideration of the radial,axial and inclined composite movements of the inner ring was established,and the nonlinear vibration characteristics of rotor-bearing systems under the influence of radial force,bearing clearance and other factors were studied.The results show that the response of the coupling system has rich nonlinear motion forms;the characteristics are closely related to radial force and bearing clearance;the unbalanced response characteristics under different radial forces are distinct.(3)On the basis of the Full Vector Spectrum theory,the unbalanced response of cantilever rotor supported by simple support and rolling bearing was analyzed.The applicability of dynamic balancing based by influence coefficient method was evaluated with the main vibration vector and vector phase angle as the main evaluation indicators.The unbalanced response characteristics of displacement and supporting force of the rotor-bearing coupling system under the influence of radial force,gravity direction and unbalance position were studied.The results show that the whole vector parameters can better reflect the change of imbalance,and the unbalanced response curve under nonlinear support is relatively complex.(4)Aiming at the coupling problem between rotor and fluid seal under large eccentricity,the rotor-bearing-seal coupling system based on nonlinear sealing force theory is established.The unbalanced response law of the "wet " cantilever rotor under the influence of radial force,sealing parameters is studied.The results show that the increasement of the unbalance and radial force to a certain extent is conducive to inhibiting the occurrence of half-frequency vortex.The radial force has a significant influence on the unbalanced response of the "dry" and "wet" rotor.In the range of small unbalance,the main vabration vector shows non-linear changes and the vector phase deviation is prominent with the increasement of unbalance value,which provides certain theoretical guidance for the high-precision field dynamic balance of low-vibration pumps.