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Research Papers: Other (Seals, Manufacturing)

Experimental Analysis of Small Diameter Brush Seals and Comparisons With Theoretical Predictions

[+] Author and Article Information
Lilas Deville, Mihaï Arghir

PPRIME Institute,
UPR CNRS 3346,
Université de Poitiers,
ENSMA ISAE,
Chasseneuil Futuroscope 86962, France

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received December 18, 2017; final manuscript received June 9, 2018; published online July 18, 2018. Assoc. Editor: Alan Palazzolo.

J. Tribol 141(1), 012201 (Jul 18, 2018) (10 pages) Paper No: TRIB-17-1486; doi: 10.1115/1.4040596 History: Received December 18, 2017; Revised June 09, 2018

The paper presents the experimental results obtained for brush seals of 38 mm diameter operating with air at pressure differences up to 7 bars and rotation frequencies up to 500 Hz. The seals had bristles of 70 μm diameter, made of Haynes 25. Seals with two radial interferences (0 and 100 μm) between the brush and the rotor were tested. The presented running in procedure underlines the influence of the initial wear on the brush temperatures. The test results consisted of leakage mass flow rates. The temperatures of a limited number of points on the brush and on the rotor were also recorded. The results confirmed the important impact of the radial interference on the leakage. The test data were further confronted with theoretical predictions obtained with an original model. The model considers the brush as a deformable porous medium. Its local porosity and permeability are obtained from a fluid–structure interaction between the bristle pack and the leakage flow. The comparisons showed nearly close values of the mass flow rates. The differences between experimental and theoretical predictions are considered to be due to an underestimation of the porosity because the model neglects the friction forces between bristles and between the bristles and the rotor.

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References

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Figures

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Fig. 5

Frame of the thermal camera and measuring points

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Fig. 6

Temperature variation during the two running in at 100 Hz and 2 bars of pressure drop

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Fig. 7

Temperature variation during the two running in at 400 Hz and 4 bars of pressure drop

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Fig. 4

Instrumentation of the test rig

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Fig. 3

Test cartridge installed in the casing

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Fig. 1

Schematic view of the brush seal

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Fig. 18

The simulated brush cell

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Fig. 8

Mass flow rate measured for two seals mounted with 100 μm radial interference versus the pressure drop and for different rotation frequencies

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Fig. 9

Variation of the averaged mass flow rates for two seals mounted with 100 μm radial interference versus the rotation speed and for different pressure drops

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Fig. 10

Amplitude of rotor dynamic displacements for brush seals with 100 μm interference

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Fig. 11

Mass flow rate measured for two seals mounted without interference versus the pressure drop and for different rotation speeds

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Fig. 12

Variation of the averaged mass flow rates for two seals mounted without interference versus the rotation speed and for different pressure drops

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Fig. 13

Comparison between the averaged mass flow rates of a single seal for the two tested interferences

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Fig. 14

Temperature measurements on the video clips given by the thermal camera

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Fig. 15

Temperature variations for 100 Hz rotation speed (seal with 100 μm radial interference)

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Fig. 16

Temperature variations for 500 Hz rotation speed (seal with 100 μm radial interference)

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Fig. 17

Temperature variations at 100 Hz without interference

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Fig. 19

The computational domain

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Fig. 20

Comparison between the experimental results obtained with 100 μm interference, the numerical calculations realized with 7 and 8 bristles in y–direction, and the simplified model from Ref. [5]

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Fig. 21

Porosity field in a section of the brush, ΔP = 1 bar, 7 bristles in y direction

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Fig. 22

Porosity field in a section of the brush, ΔP = 5 bar, 7 bristles in y direction

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Fig. 23

Deformed brush geometry for ΔP = 5 bar

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