0
Research Papers: Gas Turbines: Structures and Dynamics

Labyrinth Seal Leakage Tests: Tooth Profile, Tooth Thickness, and Eccentricity Effects

[+] Author and Article Information
Ahmed J. Gamal

Turbomachinery Laboratory, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843ajmg@aggienetwork.com

John M. Vance

Turbomachinery Laboratory, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843jvance@tamu.edu

J. Eng. Gas Turbines Power 130(1), 012510 (Jan 11, 2008) (11 pages) doi:10.1115/1.2771571 History: Received April 26, 2007; Revised May 07, 2007; Published January 11, 2008

The effects of two seal design parameters, namely blade (tooth) thickness and blade profile, on labyrinth seal leakage, as well as the effect of operating a seal in an off-center position, were examined through a series of nonrotating tests. Two reconfigurable seal designs were used, which enabled testing of two-, four-, and six-bladed see-through labyrinth seals with different geometries using the same sets of seal blades. Leakage and cavity pressure measurements were made on each of 23 seal configurations with a in.(101.6mm) diameter journal. Tests were carried out with air as the working fluid at supply pressures of up to 100psia (6.89bar). Experimental results showed that doubling the thickness of the labyrinth blades significantly influenced leakage, reducing the flow rate through the seals by up to 20%. Tests to determine the effect of blade-tip profile produced more equivocal results, with the results of experiments using each of the two test seal designs contradicting each other. Tests on one set of hardware indicated that beveling blades on the downstream side was most effective in limiting leakage, whereas tests on newer hardware with tighter clearances indicated that seals with flat-tipped blades were superior. The test results illustrated that both blade profile and blade thickness could be manipulated so as to reduce seal leakage. However, an examination of the effects of both factors together indicated that the influence of one of these parameters can, to some extent, negate the influence of the other (especially in cases with tighter clearances). finally, for all configurations tested, results showed that leakage through a seal increases with increased eccentricity and that this phenomenon was considerably more pronounced at lower supply pressures.

Copyright © 2008 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Ten-bladed labyrinth seal

Grahic Jump Location
Figure 2

Labyrinth seals with square and tapered blades

Grahic Jump Location
Figure 3

Ten-bladed pocket damper seal

Grahic Jump Location
Figure 4

Four-bladed pocket damper (left) and six-bladed labyrinth (right) test seals

Grahic Jump Location
Figure 5

High-pressure pocket damper tests seals

Grahic Jump Location
Figure 6

Nonrotating seal testrig (sectioned model view)

Grahic Jump Location
Figure 7

Seal Set A: Modified two-bladed air-buffer labyrinth seal base unit (left) and six-bladed seal (right)

Grahic Jump Location
Figure 8

New reconfigurable seal components (Seal Set B)

Grahic Jump Location
Figure 9

Nonrotating testrig (seal not installed)

Grahic Jump Location
Figure 10

Beveled blades for new (left) 1.27mm tip, 3.18mm base and old (right) 1.14mm tip, 1.91mm base seals

Grahic Jump Location
Figure 11

Seal leakage (four and six blades, long pitch)

Grahic Jump Location
Figure 12

Four-bladed seals with single—(left) and double—(right) thickness blades (blade spacing maintained constant)

Grahic Jump Location
Figure 13

Blade thickness effect (four blades, long pitch)

Grahic Jump Location
Figure 14

Blade thickness effect (four blades, short pitch)

Grahic Jump Location
Figure 15

Effect of doubling blade thickness on leakage through seals with short and long pitch lengths

Grahic Jump Location
Figure 16

Effect of blade profile on leakage (two blades)

Grahic Jump Location
Figure 17

Effect of blade profile on leakage (four blades)

Grahic Jump Location
Figure 18

Effect of blade profile on leakage (six blades)

Grahic Jump Location
Figure 19

Pressure in third cavity of four-bladed seal

Grahic Jump Location
Figure 20

Pressure in third cavity of six-bladed seal

Grahic Jump Location
Figure 21

Pressure in fifth cavity of six-bladed seal

Grahic Jump Location
Figure 22

Effect of blade profile on leakage (four blades, long pitch)

Grahic Jump Location
Figure 23

Effect of blade profile on leakage (four blades, short pitch)

Grahic Jump Location
Figure 24

Increased flow rates due to eccentricity for three seal configurations

Grahic Jump Location
Figure 25

Six-bladed test seal with shallow cavities (cavity inserts installed) and intermediate pitch

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In