Static and Dynamic Characteristics of Eccentric Labyrinth Seals

The three-dimensional numerical analysis model of labyrinth seals with different eccentricities was established. The identification method based on infinitesimal theory was applied to calculate the static and dynamic characteristics of the seal. The results showed that the eccentricity of the rotor reduced the leakage performance. The high point of the circumferential pressure in the seal cavity deviated from the minimum clearance with the increasing eccentricity. At low eccentricity (≤ 0.5), the static direct stiffness K and static cross-coupled stiffness k showed little variation, while the K and the absolute values of k decreased at high eccentricity (> 0.5). With the increase of eccentricity, the increase of flow viscosity effect on the minimum clearance was the main reason for the negative static direct stiffness. When the rotor whirled with an eccentricity, the stiffness coefficient and the damping coefficient showed little variation at low eccentricity(< 0.6), and the direct stiffness gradually developed to be negative with the increasing eccentricity and whirling frequency. With the increasing eccentricity, the cross-coupled stiffness was no longer equal in the orthogonal directions. The effective damping at high eccentricity (≥ 0.6) was more significantly affected by eccentricity.