Abstract: A numerical analysis model of the Interlocking Labyrinth Seal (ILS) is established to study the effect of shaft misalignment on the rotordynamic performance of the ILS. The rotordynamic identification method based on infinitesimal theory and computational fluid dynamics method are employed to obtain the static and dynamic characteristics. Results show that the shaft misalignment could reduce the leakage of the ILS, for instance, by approximately 2.5% at the misalignment angle of 0.6°, and that higher-pressure ratios lead to more significant effect. The geometric deformation of the ILS chambers caused by shaft misalignment and the radial clearance changes of the teeth result in uneven distribution of the chamber pressure at the circumferential direction, and the pressure also increases with the growing tilt angle. The effect of each chamber in the ILS on the stability of the system is different, which is related to the cavity geometry of the ILS. The cavity with the inlet close to and the outlet away from the rotor improves the system stability since its locally existing flow field is opposite to the direction of rotation. Otherwise, the stability will be reduced. The effective damping of the entire ILS increases as the misalignment angle increases. Shaft misalignment at the center of the seal section appears not to reduce the stability of the ILS.

Key words: interlocking labyrinth seal, computational fluid dynamics, dynamic characteristics, leakage characteristics, shaft misalignment