Flow Visualization in a Simulated Brush Seal

Braun, M. J.; Hendricks, R. C.; Canacci, Victor A.

doi:10.1115/90-gt-217

Cited by 27 publications

(12 citation statements)

References 6 publications

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“…Coking may result in generation of carbon deposits that stick on the blades of the compressor causing performance degradation as well as increased maintenance cost. Early studies of brush seals in liquid flow were performed by Braun et al [3][4][5][6]. Carlile et al [7] and Hendricks et al [8] have studied brush leakage performance with liquid helium and have reported improved performance when a lubricant is applied to the bristles.…”

Section: Introductionmentioning

confidence: 99%

Non-Metallic Brush Seals for Gas Turbine Bearings

Bhate

Thermos

Akşit

et al. 2004

Volume 4: Turbo Expo 2004

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A non-metallic brush seal has been developed as an oil seal for use in turbomachinary. Traditionally labyrinth-type seals with larger clearances have been used in such applications. Labyrinth seals have higher leakage rates and can undergo excessive wear in case of rotor instability. Brush seals reduce leakage by up to an order of magnitude and provide compliance against rotor instabilities. Brush seals are compact and are much less prone to degradations associated with oil sealing. This paper describes the benefits and development of the non-metallic brush seals for oil sealing application.

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Section: Introductionmentioning

confidence: 99%

Non-Metallic Brush Seals for Gas Turbine Bearings

Bhate

Thermos

Akşit

et al. 2004

Volume 4: Turbo Expo 2004

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show abstract

“…Variations in brush thickness are introduced into the correlation model (Braun et al, 1990;Hendricks et al, 1992; 1997) for the ideally spaced brush. The model requires the thicknesses at the interface, at the fence, and at the clamp points in order to characterize the brush.…”

Section: Comments On Porosity Determinationmentioning

confidence: 99%

“…However, several types of flow pattern emerge in fabricated bristle arrays (Braun et al, 1990), and photographs of the unpacked outside seal at 50 and 64 (not shown) revealed several void areas that had little geometric similarity yet had nearly the same unpacked porosity. It is also known, from the CFD calculations and experimental data near wall boundaries, that the Reynolds numbers become significantly higher because of the increased leakage and that recirculation patterns appear (Hendricks et al, 1992;Braun et al, 1990). Similarly, the propensity for rivering and vortical flows is enhanced for ill-ordered arrays.…”

Section: Effects On Future Computational Effortmentioning

confidence: 99%

Bidirectional Brush Seals – Post‐Test Analysis

Hendricks

Wilson²,

et al. 1998

International Journal of Rotating Machinery

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A post-test analysis of a set of inside-diameter/outside-diameter (ID/OD) bidirectional brush seals used in three-port wave rotor tests was undertaken to determine brush bristle and configuration wear, pullout, and rotor coating wear. The results suggest that sharp changes in the pressure profiles were not well reflected in bristle tip configuration patterns or wear. Also, positive-to-negative changes in axial pressure gradients appeared to have little effect on the backing plates. Although the brushes had similar porosities, they had very different unpacked arrays. This difference could explain the departure of experimental data from computational fluid dynamics flow predictions for well-packed arrays at higher pressure drops. The rotor wear led to “car track” scars (upper and lower wear bands) with a whipped surface between the bands. Those bands may have resulted from bristle stiffening at the fence and gap plates during alternate portions of the rotor cycle. Within the bristle response range the wear surface reflected the pressure distribution effect on bristle motion. No sacrificial metallurgical data were taken. The bristles did wear, with correspondingly more wear on the ID brush configurations than on the OD configurations; the complexity in constructing the ID brush was a factor.

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“…Experimental testing of brush seals has resulted in an improvement of the understanding of the internal fluid mechanics. Flow visualization tests have confirmed that the flow is highly chaotic and many vortices are formed due to the "flow over cylinder" around the bristles (Braun, Hendricks, & Canacci, 1990). CFD studies have also been an effective modeling tool in the design and analysis of brush seals.…”

Section: Overviewmentioning

confidence: 91%

“…It is commonly accepted that the flow within the seal, particularly within the bristle pack is chaotic and varies greatly with the application, fluid type, operating conditions, and seal design. A paper by Braun, Hendricks, and Canacci (Braun, Hendricks, & Canacci, 1990) describes a flow visualization technique that was used to provide insight. A linear seal configuration was tested in both an oil tunnel and a water tunnel.…”

Section: Prior Workmentioning

confidence: 99%

Computational Porous Media Modeling of a Brush Seal for Incompressible and Slightly Compressible Flow

Gresham¹

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Annular seals are critical to the efficient operation of turbomachinery under increasingly high pressure loadings. Brush seals employ rows of bristles to close the gap between the rotor and the stator in rotating machinery. They typically handle larger pressure differentials and have demonstrated lower leakage than comparable labyrinth seals. However, an understanding of the complex nature of the flow within these seals is limited. This is primarily due to the difficulty associated with modeling the flow through the bristle pack.Traditionally, the performance modeling of annular seals has been accomplished by the use of bulk flow theory. This method is relatively simple to implement but can be problematic due to the fundamental assumptions required to reduce the governing equations to a solvable form. More recent studies have used full three-dimensional computational fluid dynamics models and finite element models to simulate the behavior of the bristles and their influence on the flow through the seal. This method typically provides more information than is necessary for standard design and analysis problems faced by engineers in the turbomachinery industry. Simulations of this type also require a great deal of time and knowledge from the user in order to be of any use and are very computationally expensive. Porous media modeling techniques have also proven effective, but their application has remained limited due to the uncertainty of how to estimate the permeability terms and a lack of a simple computer code appropriate for the problem.In this thesis, a new approach is presented using a simplified porous media-based model. The governing equations are formulated in terms of pressure distribution and then discretized using finite differences. An algorithm is developed to model situations of incompressible flow as well as compressible flow under isothermal conditions. The code is then analyzed to demonstrate its performance capabilities and utility for modeling flow through a standard brush seal. Properties of the numerical scheme are demonstrated and potential limitations are addressed.iii

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Flow Visualization in a Simulated Brush Seal

Cited by 27 publications

References 6 publications

Non-Metallic Brush Seals for Gas Turbine Bearings

Non-Metallic Brush Seals for Gas Turbine Bearings

Bidirectional Brush Seals – Post‐Test Analysis

Computational Porous Media Modeling of a Brush Seal for Incompressible and Slightly Compressible Flow

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