Leakage from labyrinth seals under stationary and rotating conditions

Elgamal, Hassan; Awad, Taher; Saber, Esmail M.

doi:10.1016/0301-679x(95)00043-4

Cited by 20 publications

(13 citation statements)

References 2 publications

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“…In Alford's analysis of steam flow exciting forces, the uneven force on rotor produced by steam can easily cause the eccentricity of the rotor, which results in circumferential uneven leakage flow and continuously aggravates the whirl motion of rotor [1]. To analyse the mechanism of steam exciting force, many different computational models of seal have been used by scholars [2] to [6]. With the deepening of research, the computational models of seal for steam flow exciting forces are constantly improved [7] and [8].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Cao

2020

SV-JME

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In order to study the steam flow excited vibration caused by the eccentricity of a rotor, three-dimensional rotor whirl motion is simulated based on mesh deformation. The mechanism of steam flow excited vibration and its influence on the dynamic characteristics of the rotor are investigated. The results show that the exciting forces change with the displacement of the rotor’s centre. Rotor dynamic coefficients are nonlinear when the rotor whirls pass the mesh deformation. The rotor dynamic coefficients and effective damping increase with the increase of whirl frequency. When the whirl frequency is 24.41 Hz, the rotor dynamic coefficients are strongly affected by rotational velocity. The maximum fluctuations of average direct stiffness, cross-coupling stiffness, direct damping and cross-coupling damping are 8.1 %, 113.2 %, 45.8 %, and 121.0 %, respectively. Effective damping fluctuates greatly when both whirl and rotational frequency are 24.41 Hz. The direct stiffness, direct damping, and effective damping increase with the increase of pressure ratio, which can improve rotor stability. The pressure fluctuation on the rotor’s surface is a primary reason for steam flow excited vibration. The stability margin of the rotor can be estimated precisely via effective damping.

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Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Cao

2020

SV-JME

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“…In general, labyrinth seals were used, since their teeth serve as fluid blocking walls, resulting in improved sealing performance. 2 Labyrinth seals have been thoroughly researched. 2,3 El-Gamal et al 2 estimated the labyrinth seal performance according to the geometry of labyrinth based on the continuity and momentum equation.…”

Section: Introductionmentioning

confidence: 99%

“…2 Labyrinth seals have been thoroughly researched. 2,3 El-Gamal et al 2 estimated the labyrinth seal performance according to the geometry of labyrinth based on the continuity and momentum equation. In the up-the-step seal, the rotational speed had a good effect on labyrinth performance, but it was found to have an adverse effect on the performance of the grooved shaft and casing cases.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the rotordynamic characteristics of a single brush seal using least-squares and instrumental variable methods under super-heated steam environment

Byun

et al. 2020

Advances in Mechanical Engineering

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The exact understanding of the dynamic characteristic of the seal is a crucial parameter for designing the system. This article presents an experiment that estimates the dynamic characteristics of a brush seal under a super-heated steam environment for a steam turbine. The super-heated steam facility makes super-heated steam (523.15 K) to replicate the real steam turbine environment. Two brush seal units are utilized with a housing connected by springs to measure the modal parameters of the system. To extract the brush seal characteristics, the modal parameters of the pure housing were subtracted from the overall dynamic system. Moreover, to predict modal parameters more accurately, the least-squares method and the instrumental variable method were used to reduce the noise caused by the steam. Two major effects were experimentally investigated by varying the operating speed (0–16,900 r/min) of the rotor and the injection flow of super-heated steam. The results showed that the direct stiffness and damping of the brush seal increased significantly when the steam was injected. Under steam exposure, obtaining the modal parameters using instrumental variable method was confirmed to reduce more noise than obtaining the parameters via least-squares method.

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“…The potential for development in labyrinth seals performance for high pressure ratio gas turbines have been discussed by Stocker [1], however a comparison with data derived from detailed measurements in test facility are reported by Wittig et al [2]. Although the leakage flow through labyrinth seals under stationary and rotating conditions has been examined by El-Gamal et al [3]. Sriti et al [4] investigated the purpose of controlling better the flows within the labyrinth seals and to determine their static (leakage-pressure) and dynamic (stiffness and damping coefficients) characteristics.…”

Section: Introductionmentioning

confidence: 99%

Fluid Thermal Effect on Non-contacting Labyrinth Seal of 20 MW Steam Turbine

Mammar

Yahiaoui

Ladjedel

et al. 2019

Period. Polytech. Mech. Eng.

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This paper is divided into two parts; the first describes a CFD analysis of a gland packing labyrinth seals in 20 MW steam turbine in LNG plant using ANSYS CFX code as an isothermal simulation in fluid domain. The results of two turbulence models k-ε and k-ω SST are compared and validated against experimental data. It is shown that the labyrinth seal leakage is proportional to the clearance cube so any variation in clearance can have a significant impact on the steam leakage. This clearance between the shaft and the labyrinth seal vary as a function of operating temperature due to the different rates of thermal expansion of the materials for these two components. Likewise the fluid temperature has a direct effect on fluid dynamic behavior. For that; the second part of the paper investigates the effect of fluid thermal conditions of the labyrinth seal via the heat transfer and Nusselt number variation in the stator and the rotor, for different cases of inlet temperature (400 °C, 200 °C, 100 °C, 50 °C) and pressure ratio (2.5, 4.5, 6.5) for an ideal gas. Also it is important to know the temperature distribution across tooth and cavities of the labyrinth seal, and finally the Influence of Inlet total temperature on fluid pressure drop in the labyrinth seal will be treated for improving and readjusting the steam turbine sealing system.

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Leakage from labyrinth seals under stationary and rotating conditions

Cited by 20 publications

References 2 publications

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Estimation of the rotordynamic characteristics of a single brush seal using least-squares and instrumental variable methods under super-heated steam environment

Fluid Thermal Effect on Non-contacting Labyrinth Seal of 20 MW Steam Turbine

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