Test Results for Liquid “Damper” Seals Using a Round-Hole Roughness Pattern for the Stators

[+] Author and Article Information
Dara W. Childs

Turbomachinery Laboratory, Texas A&M University, College Station, TX 77843

Patrice Fayolle

Société Européenne de Propulsion, Division Grosse Propulsion Liquide, B.P. 802, 27207 Vernon, France

J. Tribol 121(1), 42-49 (Jan 01, 1999) (8 pages) doi:10.1115/1.2833809 History: Received September 02, 1997; Revised December 29, 1997; Online January 24, 2008


Test results are reviewed for two annular liquid seals (L = 34.9 mm; D = 76.5 mm) at two clearances (.1 and .12 mm). The seal stators use hole-pattern-roughened stators that are identical except for hole depths of .28 and 2.0 mm. Tests are conducted at three speeds out to 24,600 rpm and three pressures out to 68 bars. Test data consist of leakage rates and rotordynamic coefficients at centered and eccentric positions with static eccentricity ratios out to 0.5. Test results are consistent with expectations in regard to the reduction of cross-coupled stiffness coefficients due to stator roughness. However, the measured direct stiffness coefficients were unexpectedly low. A partial explanation for these results is provided by measured friction factor data which show an increase in the friction factors for pressure-driven flow with an increase in clearance. A prediction model for rotordynamic coefficients, incorporating the friction-factor data, predicted a substantial loss in direct stiffness but could not explain the very low (or negative) values that were measured. The model did explain the measured drop in cross coupled stiffness (k) and provides an alternative explanation to observed reductions in k values; specifically, an increase in the friction factor with increasing clearance causes a reduction in k irrespective of any parallel reduction in the average circumferential velocity.

Copyright © 1999 by The American Society of Mechanical Engineers
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