Flow Conditioning to Control the Effects of Inlet Swirl on Brush Seal Performance in Gas Turbine Engines

Liu, Yuxin; Wei, Dong; Chew, John W.; Pekris, Michael J.; Yue, Benzhuang; Kong, Xiaozhi

doi:10.3389/fenrg.2021.815152

Cited by 6 publications

(2 citation statements)

References 27 publications

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“…It can be seen that the axial force is much larger than the orthogonal force, although both are critical in determining bristle blowdown and backing ring and shaft reaction force magnitudes. The force distribution observed here is comparable to previous CFD solutions [30][31][32]. The axial force increases from the fixed bristle end (normalized coordinates = 0) until reaching the maximum near the backing ring edge.…”

Section: Analyses With Cfd-based Aerodynamic Loadingsupporting

confidence: 87%

Insights Into Frictional Brush Seal Hysteresis

Phan,

Pekris,

Chew

2024

Journal of Engineering for Gas Turbines and Power

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Brush seals offer a superior sealing effectiveness compared to labyrinth seals. However, widespread use of brush seals is constrained by deleterious behaviors such as pressure-stiffening and hysteresis. For the latter, the bristles bend during the shaft incursion process and do not fully recover during the shaft retraction process. An opening gap is created, which increases seal leakage unless the pressure load drops to a certain level. In the present work, analytical and numerical models based on a single bristle are proposed to capture the seal's response to shaft displacement with and without pressure loading. The models are validated using static stiffness tests at an unpressurized condition from literature. The main results show that modeling of the backing ring friction is essential to capture the bristle hang-up behavior. Shaft friction dominates at unpressurized conditions, while backing ring friction dominates at high pressure loading. An expression for shaft hang-up displacement has been derived. A sensitivity study shows that seals with shallow lay angle, short bristle length, and large bristle diameter are less prone to hang-up problems. The models developed in the present framework have been shown to qualitatively capture the pressure stiffening, hysteresis, bristle hang-up, and shaft rotation effects.

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Section: Analyses With Cfd-based Aerodynamic Loadingsupporting

confidence: 87%

Insights Into Frictional Brush Seal Hysteresis

Phan,

Pekris,

Chew

2024

Journal of Engineering for Gas Turbines and Power

View full text Add to dashboard Cite

show abstract

Section: Analyses With Cfd-based Aerodynamic Loadingsupporting

confidence: 87%

Insights Into Frictional Brush Seal Hysteresis

Phan,

Pekris,

Chew

2023

Volume 7B: Heat Transfer — General Interest/Additive Manufacturing Impacts on Heat Transfer; Internal Air Systems; Internal Coo

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Brush seals offer a superior sealing effectiveness compared to labyrinth seals. However, widespread use of brush seals is constrained by deleterious behaviors such as pressure-stiffening and hysteresis. For the latter, the bristles bend during the shaft incursion process and do not fully recover during the shaft retraction process. An opening gap is created, which increases seal leakage unless the pressure load drops to a certain level. In the present work, analytical and numerical models based on a single bristle are proposed to capture the seal’s response to shaft displacement with and without pressure loading. The models are validated using static stiffness tests at an unpressurized condition from literature. The main results show that modeling of the backing ring friction is essential to capture the bristle hang-up behavior. Shaft friction dominates at unpressurized conditions, while backing ring friction dominates at high pressure loading. An expression for shaft hang-up displacement has been derived. A sensitivity study shows that seals with shallow lay angle, short bristle length, and large bristle diameter are less prone to hang-up problems. The models developed in the present framework have been shown to qualitatively capture the pressure stiffening, hysteresis, bristle hang-up, and shaft rotation effects.

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Effects of geometrical parameters on bristle mechanical characteristics and deflection behavior of brush seals in gas turbine engines

Yue,

Liu,

Kong

et al. 2024

Physics of Fluids

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Within the engine air system, the sealing is pivotal for augmenting engine thrust and efficiency. The brush seal, a contact-based sealing structure, exhibits commendable sealing efficacy. Nevertheless, the supple bristles tend to slip circumferentially in swirl inlet, diminishing the seal's stability and thus constraining its applicability. This study employs a fluid–structure interaction approach to initially dissect the flow field dynamics within the bristles in swirling conditions, examining the aerodynamic behavior across various bristles and their consequent motion and deformation. Leveraging the Design of Experiment method, typical geometric variables of brush seals, such as the diameter, length, inclined angle, rows, radial clearance of bristles, and the spacing between bristles, are scrutinized, and their influence on aerodynamic force distributions on the first row of the bristles and the interplay among these parameters assessed. It was observed that under the swirl inlet imposed, the first row of bristle pack experiences diminished axial forces compared to no-swirl. The diameter of bristle emerged as a primary factor impacting axial aerodynamic force, contributing 33% of the force, and there exists a linear correlation between diameter and axial aerodynamic force. Notably, the interplay between bristle diameter and inclined angle significantly influences axial forces and bristle deformation. The critical factors influencing the normal aerodynamic force acting on the bristles were identified as the spacing and diameter of the bristles, with respective contribution rates of 27.4% and 27.3%. A linear escalation in the normal aerodynamic force is seen with increasing spacing and diameter. Additionally, a substantial inverse relationship between diameter and inclined angle was discerned.

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Flow Conditioning to Control the Effects of Inlet Swirl on Brush Seal Performance in Gas Turbine Engines

Cited by 6 publications

References 27 publications

Insights Into Frictional Brush Seal Hysteresis

Insights Into Frictional Brush Seal Hysteresis

Insights Into Frictional Brush Seal Hysteresis

Effects of geometrical parameters on bristle mechanical characteristics and deflection behavior of brush seals in gas turbine engines

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