A recent CFD perturbation model for turbomachinery seal rotordynamics was extended for labyrinth shunt injection with an arbitrarily high pressure gas. A large number of measured cases with labyrinth injection pressure at approximately 13.8 bars (200 psi) were computed and compared with measurements. The drastically reduced (negative) cross-coupled stiffness, which is the primary advantage from the use of shunt injection in gas labyrinth seal applications, was well predicted. The agreement with measurements for k⁠, C⁠, and Ceff was within about 40%, 60% and 10%, respectively. In addition, it was found that moving the injection toward the high pressure end of the seal gives k⁠, C⁠, and Ceff values that are rotordynamically only slightly more stabilizing. Further, the radial distributions of the flow perturbation quantities give support to the two-control volume approach for developing bulk-flow models for labyrinth seal rotordynamics.

Issue Section:
Gas Turbines: Structures and Dynamics
Keywords:
seals (stoppers), gas turbines, rotors, flow simulation, perturbation theory, stability, elasticity, pressure
Topics:
Flow (Dynamics), Pressure, Rotors, Rotordynamics, Stiffness, High pressure (Physics), Computational fluid dynamics
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