Simulation Research On Dynamics Of Dry Gas Seal Based On Impeller Rotor System

With the development of economy,the sealing equipment has been updated.Dry gas seals,which have the advantages of no wear,low power consumption and less leakage,are becoming more and more popular,and are widely used in various fields.In compressors with a dry gas seal as the sealing mechanism,the impeller rotor’s excitation force due to internal flow field fluid-solid coupling and other factors during high-speed operation,or the system’s centrifugal force due to unbalance,etc.,will inevitably cause equipment system vibration In turn,it interferes with the dr y gas seal and causes the gap to change,which is very likely to cause friction and collision between the dynamic and static rings.In severe cases,the dry gas seal will fail and the equipment will not operate normally.Therefore,in order to ensure the s tability of the dry gas seal or the device,the dynamic characteristics of the dry gas seal based on the actual operating conditions of the large system urgently need to be explored.To study the dynamic characteristics of dry gas seals based on impeller r otor systems,the study of the gas film stiffness between dry gas seals is essential.In this paper,SolidWorks 3D modeling software is used to geometrically model the gas film with different gas film thickness,groove depth,groove number and helix angle,and the mesh is divided using ICEM software,and then FLUENT software is used to simulate the flow field.Calculate the opening force corresponding to the gas film of different structural parameters respectively,use the principle of least squares to fit the polynomials of the opening force and different structural parameters,and derive the polynomial about the thickness of the gas film to obtain the gas film stiffness and different structural parameters Relationship.By comparing the change curve of gas film stiffness,it is found that the gas film stiffness decreases with the increase of gas film thickness,and gradually stabilizes.When the groove depth is 12μm,the number of grooves is 12,and the spiral angle is 22°,the rigid film performance of th e dry gas seal gas film reaches the best.Taking the impeller rotor-bearing-dry gas seal system shaft system as the research object,using SolidWorks for geometric modeling,considering the rotor gyro effect,the critical speed of the shaft system is calcu lated,and the first-order and second-order critical speed of the shaft system are obtained as 13744 r·min^-1,34380r·min^-1;the critical speed calculation of the shaft system with different bearing stiffness,the research shows that as the bearing stiffness increases,the critical speed also increases and becomes stable;Based on the theory,calculate the centrifugal force caused by the maximum allowable unbalance at the maximum working speed as the excitation load,and analyze the harmonic response of the shaft system.The research shows that the shaft system will be at the first natural frequency and the second natural frequency under the excitation.Resonance occurred,which verified the accuracy of the calculation of the natural frequency of the shaftin g.In order to explore the axial vibration characteristics of the dry gas seal based on the impeller rotor system,mathematical modeling and geometric modeling were used to demonstrate and analyze.Based on the characteristics of the dry gas seal structure,the axial vibration model of the impeller rotor-bearing-dry gas seal system is established,and the undetermined coefficient method is used to solve,and the expression of the axial vibration amplitude of the dynamic and static ring is derived.The geometric model of impeller rotor-bearing-dry gas seal system with static ring was established,and the axial vibration simulation was simulated using ANSYS Workbench software.Combining the simulation results and theoretical results,it is found that the gas film stiffness has little effect on the vibration amplitude of the dynamic and static rings;the vibration frequency of the dynamic and static rings is the same,and the vibration amplitude is also the same.It is stable to ensure the stable operation of the dry gas seal;the amplitude of dynamic and static ring vibration is proportional to the exciting force.The greater the exciting force,the greater the displacement of the dynamic and static ring vibration.