Rotordynamic Performance of the Interlocking Labyrinth Seal With a Tilting Rotor

Abstract

Numerical analysis model of an interlocking labyrinth seal (ILS) is established for studying the effect of tilting rotor on its rotordynamic characteristics. The dynamic characteristic identification method based on infinitesimal theory is applied to solve the dynamic force coefficient of the seal with arbitrary elliptical orbits and eccentric positions under field conditions. The paper investigated the dynamic characteristics of the interlocking labyrinth seal with various misalignment angles (θ = 0, 0.1 deg, 0.2 deg, 0.3 deg, 0.4 deg, 0.5 deg, 0.6 deg), different pressure ratios (Pin = 6.9 bar, PR = 0.5, 0.8), locations of misalignment center (Loc = 0, L/2, L). Results show that the tilting rotor could minimize the leakage flow rate of the ILS. When the misalignment angle θ = 0.6 deg, the mass flow rate can be reduced about 2.5%. The effect of each cavity in the ILS on the stability of the system is different. The cavity with the inlet close to the rotor and the outlet away from the rotor helps to improve the system stability due to its locally antirotational flow. The effective damping of the entire ILS increases as the misalignment angle increases. The system shows the best stability when the misalignment center is close to the seal inlet. The tilting rotor has a positive effect on the stability of the ILS only except for high whirling frequency (>100 Hz) under Loc = L.