Leakage and rotordynamic performance of a mixed labyrinth seal compared with that of a staggered labyrinth seal

Minimizing unwanted leakage between stationary and rotating parts is the main function of annular seals. A Mixed labyrinth seal (MLS) with two specially designed lateral teeth installed on a Staggered labyrinth seal (SLS) is proposed to improve seal performance. A 3D computational fluid dynamics calculation model of MLS is set up. The twin vortex structure that appears in the seal cavity and flow path is more complicated in MLS than in SLS. MLS reduces leakage by about 30 % compared with SLS. Rotordynamic analysis of MLS is also conducted by calculating cross-coupled stiffness. The cross-coupled stiffness of MLS is about 75 % to 85 % that of SLS. The dependence of seal performance on the parameters of the lateral teeth is investigated through a simulation test. The lateral teeth should be set in the middle of the seal cavity, and the gap between the two lateral teeth should be similar to the tip clearance.

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