Numerical Analysis On Structure Optimization And Dynamic Flow Characteristics Of Labyrinth Seal

Labyrinth seal has a small and complex clearance structure,effectively prevent leakage of gas,and it can adapt to variable,complicated,high parameters working condition.Labyrinth seal often used as a preposition,middle and postposition seal structure in dry gas seal because of its good sealing characteristics,which make the mechanical equipment operating good and stably.But the leakage is inevitable,rotor vortex,and the uneven distribution of flow stress and temperature,which cause of the cavity’s pressure fluctuation of dry gas seal,the gas film less stable,flow vibration,rotor and sealing tooth occurring deformation and friction collision.In order to better understand the influence of labyrinth seal’s structure and dynamic flow field characteristics,this paper takes a middle labyrinth seal of dry gas seal in a chemical plant’s compressor as the research object.First of all,solving the three-dimensional N-S equations by using Fluent software when considering the effect of gas compressibility and viscosity-temperature,and analyzing the profile parameters and working parameters on the influence of the leakage,and optimizing the original structure;Then,using sliding grid interaction and interface technology,considering the rotor vortex revolution and rotation,to simulate research the unsteady flow field under different eccentric,prewhirl angle,vortex speed;Finally,using the Fluent and Workbench software to analyze to fore deformation and thermal deformation of the seal ring and the shaft.The result shows that the model sealing tooth has a best deep width ratio about 0.2 and a best after tilt angle about 20° which have nothing to do with the clearance,the optimal cavity number appears near the best depth width ratio when the seal length is fixed;The leakage increase exponential function with the raise of pressure,and decreased sharply with the increase of inlet temperature under the constant pressure difference,the leakage is a little small when considering the viscosity-temperature effect;Those physical quantities in unsteady flow field various vary with time and location with periodicity,vortex revolution can increase the turbulence intensity,the gas forces of pressure is mainly in radial and tangent upward,but the gas forces of viscous is mainly in axis upward,the proper prewhirl can increase the stability of the rotor;The sealing ring and rotor’s thermal deformation is bigger than the force deformation,the differential pressure can help to reduce the total coupling deformation but the eccentric and temperature difference is contrary,and the eccentric’s influence to coupling deformation on the clearance is small but the temperature difference is big,the axis’ s maximum deformation appears at the entrance of the minimum clearance side,and the sealing ring is at the first tooth.