Research On Transient Frictional Vibratio And Thermal-mechanical Coupling Of Dry Gas Seal

Dry gas seal is a type of non-contact mechanical seal.Compared with ordinary mechanical seals,it has shallow dynamic pressure grooves on the surface of the moving ring.The moving ring produces pumping action under the drive of the main shaft to pump upstream gas to the seal.At the interface,a stable fluid film of 3～5um is formed on the sealing interface to realize the non-contact of the sealing pair.During the start and stop of rotating equipment and special working conditions,the end face of the dry gas seal is in direct contact,causing the seal pair to be in dry friction conditions,causing serious wear on the end face of the seal ring,resulting in a large amount of frictional heat,frictional vibration and noise,and even causing the seal pair The material peeled off,causing the seal to fail.This paper analyzes and studies the friction-thermomechanical coupling and frictional self-excited vibration behavior of the seal interface under low-speed operating conditions during the start-stop phase of the dry gas seal system.In terms of friction thermodynamics,the three-dimensional morphology of the actual dry gas seal friction pair is established based on the micron-level two-way spiral groove and the arc groove,and the thermodynamic model of the seal pair under dry friction conditions is established considering the heat conduction of the seal interface.The explicit dynamic analysis method is used to analyze the dry gas.The sealing friction pair performs a complete thermal-mechanical coupling friction heat transfer analysis.The temperature field and stress field distribution and change law on the surface and inside of the friction pair under different groove types,different groove depths and different working conditions are discussed,and the surface temperature field distribution of the textured friction pair and the smooth friction pair are compared.The analysis results show that the presence of the microstructure of the friction pair causes local high-temperature hot spots on the contact surface;the maximum temperature of the dual surface increases with the increase of the speed and the running time,the more obvious the rising trend;the temperature rise of the arc groove interface is lower than that of the two-way spiral groove interface;The Von Mises equivalent stress distribution of the carbon graphite static ring contact surface is similar to the high temperature hot spot area.The thermal stress generated by the local temperature difference of the contact surface is the main factor leading to the stress concentration.The conclusions obtained provide a theoretical reference for the optimization and design of the end face structure of the dry gas seal.In the analysis of frictional self-excited vibration of the seal pair,this paper compares the frictional vibration characteristics of the non-slot dual surface,the arc groove dual surface and the bidirectional spiral groove dual surface based on the instantaneous dynamic analysis method,and uses the singular value noise reduction algorithm to analyze the frictional vibration characteristics.The vibration signal is excited to reduce noise;based on time-frequency analysis and power spectral density estimation,the spectral characteristics and energy distribution of vibration signals of different texture friction pairs are obtained.The analysis shows that the influence of the same order of magnitude of the microgroove depth on the frictional vibration characteristics of the interface can be ignored;compared with the non-grooved end surface,the groove can significantly reduce the normal vibration amplitude of the friction surface.That is to say,in actual engineering,surface texture has an inhibitory effect on frictional self-excited vibration.Using the singular value noise reduction algorithm to reduce the noise of the vibration signal can improve the signal-to-noise ratio of the vibration signal and make the calculation and analysis results more accurate.The analysis results in this paper show that the arc groove texture is better than the bidirectional spiral groove texture in restraining frictional heat generation and frictional self-excited vibration.