Study On Internal Unsteady Flow And Vibration Character Istics Of The Upstream Pumping Mechanical Seal

The upstream pumping mechanical seal is a kind of non contact seal structure with dynamic pressure effect. In recent years, many researchers have been concerned and studied. For micron seal clearance, the transient characteristics of the internal flow and the vibration characteristics of seal have a direct impact on the stability of lubricating film and sealing lubricating performance, and it is an important issues of the relationship between sealing performance and service life,and the research is still very lacking. This paper in the funding of National Natural Science Fund Project 51279067 and aviation science fund project 201328R3001,Upstream pumping mechanical seal as the research object, according to seal the inner unsteady flow characteristics and induced seal ring vibration mechanism study,ansys the regularity deformation of sealing ring and the improvement of groove type.In order to explore the non steady state of non contact mechanical seal,the main research work and conclusions are as follows.Base on the previous research work of upstream pumping mechanical seal about the internal flow field of the steady state, established unsteady flow calculation model.Using numerical analysis method for unsteady analysis of internal flow field of lubrication film to research the unsteady flow characteristics of the flow field internal pressure and the influence of speed to sealing performance.It is concluded that the strong pressure fluctuation causing by rotor-stator interaction have an important characteristic of unsteady flow, and also the main cause of the instability of the liquid film opening force.Based on the analysis of pressure pulsation characteristics of the flow field in the sealing gap, BVF is applied for further analysis of the internal flow field. It is used to explore the sealing performance and the evalua0 tion method of internal flow stability of non-contact mechanical seal, to study and verify the relationships between the improvement of the spiral groove and sealing performance, and to obtain better groove improvements. The results show that it is feasible to use the velocity field, pressure pulsation and boundary vorticity flux as a comprehensive toanalyze the stability of the sealing performance; The rounds at groove roots can enhance the dynamic pressure effect and increase opening force of the fluid film,and there is best ratio of diameter and length, Rr.Considering the effects of the transient excitations of lubricating film on the sealing ring deformation, the unsteady one-way fluid-solid coupling model of sealing ring and lubricating film is established to study the deformation law of sealing ring and the relationships between the deformation and the stability of sealing performance, and the effects of sealing groove improvement on the stability of sealing performance. Research shows that the maximum equivalent stress and maximum deformation occur at the root of the spiral groove in both models, and there are deformations in both circumferential direction and axial direction, while it is mainly on the circumferential direction.Considering the circumstances of hydraulic and mechanical factors, modal analysis was carried out on the upstream pumping mechanical seal, studying the vibration characteristic of the sealing ring and comparative analysis of the impact groove improved on the vibration characteristics.Research shows that:Under the research object and the working condition, the sealing ring is not easy to resonate;Compared with ordinary groove, after root rounded ring circumferential and axial deformation to deform more, but less affected by static ring groove, and natural frequency changes little.