Theoretical and numerical investigation into brush seal hysteresis without pressure differential

Kang, Yuchi; Liu, Meihong; Hu, Xiangping; Kao-Walter, Sharon; Zhang, Baodi

doi:10.1177/0963693519885386

Cited by 6 publications

(6 citation statements)

References 14 publications

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“…Further verification/validation works have been routinely carried out during the development of the numerical method. Extra comparisons have been made against experimental data provided by Demiroglu et al [5] and Duran et al [14,15] as well as against other researchers' models such as those by Stango et al [6,7] and Kang et al [27]. Validations for pressurized seals are particularly difficult due to scarce experimental data available in the public domain.…”

Section: Baseline Validationmentioning

confidence: 99%

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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: Baseline Validationmentioning

confidence: 99%

“…Hysteresis ratio has typically been adopted for classical mechanic studies regarding friction (for example see Israelachvili et al [29]). Kang et al [27] has also adopted this metric to investigate the hysteresis performance of brush seals.…”

Section: Figurementioning

confidence: 99%

Insights Into Frictional Brush Seal Hysteresis

Phan,

Pekris,

Chew

2024

Journal of Engineering for Gas Turbines and Power

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“…In solid mechanics, the approximate differential equation for the deflection curve is [18][19][20][21] :…”

Section: Theoretical Verificationmentioning

confidence: 99%

Numerical research on contact friction force with different structural brush seal hysteresis characteristics under differential pressure

Tang,

Liu,

Tao

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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The problems of leakage, frictional wear, and flow heat transfer caused by the hysteresis characteristics of brush seals are prominent, and existing models for solving the hysteresis characteristics of brush seals have convergence difficulties owing to the extreme degree of nonlinearity caused by additional contacts. In this study, numerical models based on the finite element software ABAQUS were proposed to address the hysteresis characteristics of brush seals with three different structures: basic, low-lag hysteresis, and low-wear high-pressure bearing. The models accounted for the contacts between: the brush, brush and the baffle, and brush and the rotor, while damping was introduced to improve the convergence of the models. The hysteresis of the three structures under differential pressure was investigated and compared with theoretical calculations and experimental test results. The hysteresis of the bristles was normalised by the contact force, the shift of the contact area, and the contact friction force when the hysteresis effect occurred in the brush seal. The results show that the basic model has the most obvious hysteresis characteristics in the presence of differential pressure. Although the low-lag hysteresis model and the low-wear high-pressure bearing model have the weakest hysteresis effect, the deformation variables of the last row of bristles of these two structures are larger than those of the basic model; therefore, the contact position is prone to fatigue fracture. Simultaneously, the hysteresis effect was verified by varying the contact area and contact friction force, and it was found that the larger the contact area and contact friction force, the larger the hysteresis.

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“…Duran et al [15,16] and Zhang [17] established a 3D calculation model of multiple bristles and simulated numerically their deformation and the contact force between them and the rotor during the loading and unloading cycle of the radial offset of the rotor. Kang et al [18] found that the lay angle of the bristles had a greater effect on the HE when the pressure difference was not considered. However, once separated, there is no contact force between the bristles and the rotor, and the deformed bristles can continue to recover; therefore, the contact force is no longer applicable for describing the deformation.…”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Numerical simulation of deformation hysteresis effect of the bristles of brush seals

Li,

Hu,

2024

J. Phys.: Conf. Ser.

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Because of their good sealing performance, brush seals are used widely in turbomachinery as alternatives to traditional labyrinth seals. However, obstructed by friction, the flexible bristles cannot recover fully after deformation, resulting in a hysteresis effect and decreased sealing performance. In the present study, a three-dimensional multi-row bristle model is established that considers the friction between the neighbouring bristles and back plate. Then the deformation and recovery of the bristles during the radial reciprocating offset of the rotor in the presence of a pressure difference are studied. To evaluate the hysteresis effect, analysis is directed at the unrecovered bristle deformation in the radial direction affected by bristle diameter, bristle lay angle, fence height and width of pressure relief chamber. The results show that the larger the bristle diameter and fence height, the weaker the hysteresis effect and the larger the bristle lay angle, the stronger the hysteresis effect. With increasing width of the pressure relief chamber, the hysteresis effect weakens and then strengthens, meaning that the pressure relief chamber has an optimal axial width that departure from enhances the hysteresis effect. The present results offer a reference for selecting the structural parameters of brush seals in engineering design.

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Theoretical and numerical investigation into brush seal hysteresis without pressure differential

Cited by 6 publications

References 14 publications

Insights Into Frictional Brush Seal Hysteresis

Insights Into Frictional Brush Seal Hysteresis

Numerical research on contact friction force with different structural brush seal hysteresis characteristics under differential pressure

Numerical simulation of deformation hysteresis effect of the bristles of brush seals

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