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A Novel Bulk-Flow Model for Pocket Damper Seals

April 26, 2019

Join Waukesha Bearings at ASME Turbo Expo 2019, June 17-21, for the presentation of "A Novel Bulk-Flow Model for Pocket Damper Seals."

Paper Number: 90059
Session: 34-16 Seals 1
Date: Monday, June 17, 8:00 AM – 10:00 AM
Presenter: Dr. Filippo Cangioli

Authors
Dr. Filippo Cangioli, Senior Applications Engineer, Waukesha Bearing Corporation
Dr. Giuseppe Vannini, Principal Rotordynamics Engineer, Baker Hughes, a GE company
Dr. Thomas Chirathadam, Engineering Manager, Bearings Plus, Waukesha Bearings

Abstract
In this paper a novel bulk-flow model for pocket damper seals (PDS) is introduced. The model is based on two control volumes for each circumferential pocket of the seal. The continuity, circumferential momentum and energy equations are considered for each control volume. The circumferential recirculating flow within the pocket is modelled for the first time. The boundary layer theory is used to estimate the recirculating flow area, and the Swamee-Jain friction factor correlation allows for defining the dissipation of the circumferential velocity. The perturbation method is used to solve the partial derivative governing equations in the zeroth and first-order system of equations. The rotordynamic coefficients are evaluated by integrating the dynamic pressure and rotor shear stresses along the circumferential direction.

The predictions are compared to the experimental data, which refer to test conditions representative of high-pressure centrifugal compressors. Numerical predictions are accurate for both high positive-negative inlet pre-swirl ratios. Leakage predictions are also aligned with measurements.

Finally, sealing selection approach is introduced in the paper for comparing the dynamic behaviour of two different sealing technologies and identifying stable regions as a function of the rotor natural frequency and pre-swirl ratio.

 Pocket Damper seal modeling