In this paper, an experimental program and a CFD based mathematical model using a brush seal at two bristle to rotor clearances (0.27 mm and 0.75 mm) are presented. The experimental program examined the radial pressure distributions along the backing ring, the axial pressure distribution along the rotor, and the mass flow through the seal through a range of pressure ratios while exhausting to atmosphere. The results from this experimental program have been used to further calibrate a CFD-based model. This model treats the bristle pack as an axisymmetric, anisotropic porous region, and is calibrated by the definition of nonlinear resistance coefficients in three orthogonal directions. The CFD analysis calculates the aerodynamic forces on the bristles, which are subsequently used in a separate program to estimate the bristle movements, stresses, and bristle and rotor loads. The analysis shows that a brush seal with a build clearance produces a very different flow field within the bristle pack to one with an interference, and the need to understand the bulk movements of the bristles. These are shown to be affected by the level of friction between the bristles and the backing ring, which has an important effect on the bristles wear and seal leakage characteristics.

Issue Section:
Gas Turbines: Heat Transfer
Topics:
Clearances (Engineering), Modeling, Computational fluid dynamics, Pressure, Rotors, Flow (Dynamics), Stress, Aerodynamics, Anisotropy, Fluid-dynamic forces, Friction, Leakage, Wear
1.
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2.
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3.
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4.
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5.
Braun
M. J.
, and
Kudriatsev
V. V.
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A Numerical Simulation of the Brush Seal Section and Some Experimental Results
,”
ASME Journal of Turbomachinery
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115
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410
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6.
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7.
Bayley
F. J.
, and
Long
C. A.
,
1993
, “
A Combined Experimental and Theoretical Study of Flow and Pressure Distribution in a Brush Seal
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
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115
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2
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8.
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9.
Long, C. A., private communications.
10.
Moore, J. G., 1985, “Calculation of 3D flow without Numerical Mixing,” AGARD Lecture Series No. 140 on 3D Computational Techniques Applied to Internal Flows in Propulsion Systems.
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