Rotordynamic-coefficient and leakage test results are presented for three grooved seals with helix angles of 0, 15, and 30 deg against rotation. The seals are 50.8 mm long and 152.4 mm in diameter. Tests were done for two supply pressures (up to 17 bars), three speeds (5000, 12,000, and 16,000 rpm), four pressure ratios, and three inlet fluid prerotation conditions. The results showed that increasing the helix angle yields a progressive reduction in the cross-coupled stiffness coefficient k and a progressive increase in leakage. The helically grooved seals consistently yield negative cross-coupled stiffness coefficients for nonprerotated inlet flow; hence, k in these seals would oppose forward whirl of a rotor. Helically grooved seals become less effective at reducing k with increasing preswirl; hence, for optimum effectiveness they should be used with a swirl brake. Comparison between helically grooved and honeycomb-stator seals showed that helically grooved stators had reduced (negative) whirl-frequency ratios for nonprerotated flows but were no better than honeycomb-stator seals for elevated fluid prerotation. The 15 and 30 deg helix grooves leaked about 1.6 and 2.2 times, respectively, as much as the honeycomb-stator seals.

Issue Section:
Gas Turbines: Structures and Dynamics
Topics:
Leakage, Stators, Honeycomb structures, Flow (Dynamics), Fluids, Stiffness, Whirls, Brakes, Pressure, Rotation, Rotors
1.
Childs
D. W.
,
Nelson
C. C.
,
Scharrer
J.
,
Elrod
D.
, and
Hale
K.
,
1986
, “
Theory Versus Experiment for the Rotordynamic Coefficients of Annular Gas Seals: Part 1—Test Facility and Apparatus
,”
ASME Journal of Tribology
, Vol.
108
, pp.
426
–
432
.
2.
Childs
D.
,
Elrod
D.
, and
Hale
K.
,
1989
, “
Annular Honeycomb Seals: Test Results for Leakage and Rotordynamic Coefficients; Comparisons to Labyrinth and Smooth Configurations
,”
ASME Journal of Tribology
, Vol.
111
, pp.
293
–
301
.
3.
Childs, D., and Elrod, D., and Ramsey, C., 1990, “Annular Honeycomb Seals: Additional Test Results for Leakage and Rotordynamic Coefficients,” in IF-ToMM, Proceedings of the Third International Conference on Rotordynamics, Lyon, France, pp. 303–312.
4.
Gansle, A. J., 1993, “A Comparison of Theoretical and Experimental Coefficients for Helically Grooved Annular Gas Seals,” M.S. Thesis, Mechanical Engineering Department, Texas A&M University.
5.
Holman, J. P., 1989, Experimental Methods for Engineers, McGraw-Hill, New York, pp. 41–42.
6.
Iwatsubo, T., Sheng, B., and Ono, M., 1990, “Experiment of Static and Dynamic Characteristics of Spiral Grooved Seals,” Rotordynamic Instability Problems in High-Performance Turbomachinery, NASA CP No. 3122, proceedings of a workshop held at Texas A&M University, pp. 223–234.
7.
Pelletti, J. M., and Childs, D. W., 1991, “A Comparison of Experimental Results and Theoretical Predictions for the Rotordynamic Coefficients of Short (L/D = 1/6) Labyrinth Seals,” ASME Design Technical Conference, Sept., ASME DE-Vol. 35, pp. 69–76.
8.
Vance
J.
,
1993
, “
A New Damper Seal for Turbomachinery
,”
Vibration of Rotating Systems
, ASME DE-Vol.
60
, pp.
139
–
148
.
9.
Walowit, J. A., 1992, “Users Manual for Computer Code SPIRALG Gas Lubricated Spiral Grooved Cylindrical and Face Seals,” NAS3-25644.
10.
Zeidan, F. Y., Perez, R. X., and Stephenson, E. M., 1993, “The Use of Honey comb Seals in Stabilizing Two Centrifugal Compressors,” presented at the 22nd Turbomachinery Symposium.
This content is only available via PDF.
Copyright © 1996
 by The American Society of Mechanical Engineers
You do not currently have access to this content.