Analysis of Sealing Bearing Induced Vibration and Comparison with Rub Faults
The vibration of a gas turbine generator unit is greatly affected by the oil inlet temperature of the sealing bearing.When the sealing oil temperature decreases,the vibration increases.There is a lag between the vibration change and the sealing oil temperature change.In order to analyze the vibration mechanism,the sealing bearing oil film force solution model is established based on short bearing theory,and the temperature gradient solution model of sealing section is established based on heat balance theory.The effects of oil temperature,eccentricity and whirling amplitude on the section temperature gradient are calculated and analyzed.It is found that the shear flow of oil in the clearance of the sealing bearing will produce a temperature difference on the rotating shaft.The temperature difference is greatly affected by oil temperature and eccentricity,but less by the whirling amplitude.When the oil temperature increases and the eccentricity decreases,the cross-section temperature difference decreases.Compared with the rub fault,the whirling amplitude has less influence on the temperature gradient.Although the vibration will change with the seal oil temperature,there is no periodic fluctuation and divergence of the vibration.This kind of unstable vibration phenomenon is well explained.
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