This is the first (Part I) of two papers describing recent results of the research program directed at developing a vibration damper suitable for high-temperature turbomachinery applications. It is expected that such dampers will replace squeeze-film dampers, which use oil as the working fluid and have limitations at higher temperatures. A novel gas-operated bearing damper has been evaluated analytically and experimentally for its damping characteristics. A theory based on the isentropic assumptions predicts the damper performance characteristics reasonably well. A maximum damping level of 2311 N-m/s (13.2 lb-s/in.) at a frequency of 100 Hz was measured with a single actuator of the gas damper. Since many such actuators could be placed circumferentially around the squirrel cage, considerable damping levels can be realized. The study also shows that significantly higher damping levels can be achieved by modifying the current design. Part I describes the theoretical model that has been developed based on isentropic assumptions. This model is an improved version of the previous theory (Vance et al., 1991) and includes the supply groove effects, dynamic area changes of the inlet feeding holes, and the effects of flow choking on damper behavior. The governing equations are derived and theoretical predictions using these equations have been made for two hardware designs that were experimentally investigated (see Part II for experimental results).

1.
Shapiro, A. H., 1953, The Dynamics and Thermodynamics of Compressible Fluid Flow, The Ronald Press Company, New York, Vol. 1, pp. 85.
2.
Sundararajan, P., 1992, “A Theoretical and Experimental Investigation of a Gas Operated Bearing Damper for Turbomachinery,” Master’s Thesis, Texas A&M University, College Station, TX.
3.
Vance
J. M.
,
Cardon
B. P.
,
San Andres
L. A.
, and
Storace
A. F.
,
1993
, “
A Gas-Operated Bearing Damper for Turbomachinery
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
115
, pp.
383
389
.
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