0
Research Papers

Improved Understanding of Blow-Down in Filament Seals

[+] Author and Article Information
Gervas Franceschini

Transmissions, Structures and Drives, Rolls-Royce plc, Derby DE24 8BJ, UKgervas.franceschini@rolls-royce.com

Terry V. Jones

Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK

David R. H. Gillespie1

Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UKdavid.gillespie@eng.ox.ac.uk

1

Corresponding author.

J. Turbomach 132(4), 041004 (Apr 26, 2010) (10 pages) doi:10.1115/1.3213552 History: Received March 02, 2009; Revised April 17, 2009; Published April 26, 2010; Online April 26, 2010

Brush seals are used to provide flow resistance between rotating and stationary components in gas turbines. Compliant filament seals, such as brush seals, exhibit a phenomenon called blow-down, where the filaments deflect toward the rotor surface when a differential pressure is applied across the seal. This phenomenon is desirable as it enables seal contact to be maintained during rotor contractions and eccentric excursions. This paper describes an aerodynamic mechanism, which can cause the blow-down of bristles. Importantly it shows that distortion of the bristle pack is not necessary to achieve blow-down. Experimental and computational investigations of a large scale model representative of a section of a brush seal are also reported. The measured and predicted detailed pressure distributions thus obtained are used to validate the model of blow-down presented.

Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Control volume for seal with angled elements

Grahic Jump Location
Figure 2

Blow-down of thin widely spaced flexible leaves in a low speed wind tunnel

Grahic Jump Location
Figure 3

Summary of flow-field main features from flow visualization

Grahic Jump Location
Figure 4

Static pressure contours over the upper and lower surfaces of the canted strip

Grahic Jump Location
Figure 5

Pressure difference distribution over the strip inclined at 45 deg

Grahic Jump Location
Figure 6

Pressure difference distribution over the strip inclined at 30 deg

Grahic Jump Location
Figure 7

Pressure difference distribution over the strip inclined at 60 deg

Grahic Jump Location
Figure 8

Flow direction changes at the strip edges

Grahic Jump Location
Figure 9

Potential flow streamlines for case with no strips

Grahic Jump Location
Figure 10

Large bristle pack in wind tunnel viewed from underneath

Grahic Jump Location
Figure 26

Flow directions at the inlet to (top) and exit from (bottom) a stream filament around the upper surface of the bristle

Grahic Jump Location
Figure 21

Comparison between CFD and experiment (first row bristle at 2.5 mm from tip)

Grahic Jump Location
Figure 20

Force acting on each bristle in the blow-down direction (1–10)

Grahic Jump Location
Figure 19

Velocity vectors on the indicated axial plane viewed from the inlet

Grahic Jump Location
Figure 18

Velocity vectors on the midchannel plane viewed from the side

Grahic Jump Location
Figure 17

Detail of the mesh around the bristle tips

Grahic Jump Location
Figure 16

Variation in pressure around bristle cross section at 2.5 mm minimum distance from tip

Grahic Jump Location
Figure 15

Pressure distribution measured over bristle surface (row 8)

Grahic Jump Location
Figure 14

Pressure distribution measured over bristle surface (row 2)

Grahic Jump Location
Figure 13

Pressure distribution measured over bristle surface (row 1)

Grahic Jump Location
Figure 12

Enlarged image of real brush seal packing

Grahic Jump Location
Figure 11

Large bristle pack in wind tunnel viewed from exit plenum chamber

Grahic Jump Location
Figure 22

Comparison between CFD and experiment (second row bristle at 7.5 mm from tip)

Grahic Jump Location
Figure 23

Pressure field mismatch between the sides of a flexible element with thickness

Grahic Jump Location
Figure 24

Velocity vectors at the inlet and exit from internal rows of bristles

Grahic Jump Location
Figure 25

Flow directions at the inlet to (top) and exit from (bottom) a stream filament around the upper surface of the bristle

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