Labyrinth Seal Flow Field And Its Dynamic Characteristics Are Calculated

Labyrinth seal is one of the common seal in the industry,with the simple configuration,strong applicability for multifarious industrial medium and long service life,so it is commonly used in revolving compressor and turbo-machinery.However, with development of turbo-machinery towards high capability and huge cubage,gas exciting vibration in labyrinth seals became the main reason threaten the security operating of the machinery set.This paper first studied on the mechanism of gas exciting vibration and the internal flow field of labyrinth seals,using FLUENT software.And then put forward a method to compute the dynamic coefficients of labyrinth seals.A popular CFD software FLUENT is used in the numerical simulation of flow fields and calculation of labyrinth seal gas forces.Three-dimensional finite element models of the labyrinth seals were established,and the suitable models were changed. The influence of grid unit and its length to width ratio to the compute result and iterative convergence was discussed.The leakage and the pressure computed from the simulation and from experiential formulas were compared.The internal three-dimension flow field of labyrinth seals was completely analyzed in this paper.The influences of rotor eccentricity,rotating speed,pressure difference to the distribution of the circumferential pressure in the wall of the sealing cavity were discussed.And the mechanism of flow induced vibration was further realized.Furthermore,the inlet pressure was defined using UDF,and the flow field was discussed under a certain total inlet pressure and a certain static inlet pressure,the gas forces under the two conditions were also compared.A method to compute the dynamic coefficients of labyrinth seals was put forward,and then the influence foctors to the dynamic characteristics of labyrinth seals were analysed,such as rotor's eccentricity,rotating speed,pressure difference,prerotation velocity.