Abstract
Labyrinth seal is a kind of untouched dynamical seal which is commonly used in turbo-machinery to reduce the leakage loss. It is a well known problem that seals fluid forces on the rotor which can excite rotor vibrations and thereby destabilize the machine. So it is vital important to simulate the gas flow and pressure distribution inside labyrinth seal in order to deeply study the destabilization mechanism and the influence factors.
The flow inside labyrinth seal obeys all the conservation equations of fluid flow for mass, momentum and energy. 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.
Keyword: Labyrinth seal, Rotor dynamics, Flow field
