Labyrinth Seal Literature Survey

Sneck, H. J.

doi:10.1115/1.3452498

Cited by 21 publications

(18 citation statements)

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“…: Width of the seal tooth C : Initial (static cold) clearance C 1 : Reduced operating clearance due to CG alone C 2 : Net reduced operating clearance due to combined CG &TG CG…”

Section: Nomenclature-mentioning

confidence: 99%

“…[1][2][3][4][5], pertaining to plain annular seals, labyrinth seals, brush seals and advanced seals used in gas turbine secondary air systems. The work by Wittig et al [6] contained static rig experiments as well as numerical investigations for geometrically similar straight through and stepped seals of converged and diverged configurations.…”

Section: Introductionmentioning

confidence: 99%

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Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal

2015

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Leakage characteristics, influenced by centrifugal and thermal radial growth are determined computationally for a generic rotating labyrinth seal used in the gas turbine secondary air system. Three seal locations, namely, R25, R50 and R75 are represented by means of varying the rotor radius mimicking different radial positions of the seal from the shaft axis. The combined influence of seal location and its radial (Centrifugal and thermal) growth on the leakage performance is investigated for a wide-ranging speeds from 1000 to 3000 rad/s, temperatures ranging from 200 to 450 o C and pressure ratios varying from 1.1 to 2.5, for a chosen initial clearance of 500 micron. A comparison of the effect of rotation and temperature gradient among different rotors shows that the radial growth and leakage flow rates significantly vary with the increasing radius.

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“…: Width of the seal tooth C : Initial (static cold) clearance C 1 : Reduced operating clearance due to CG alone C 2 : Net reduced operating clearance due to combined CG &TG CG…”

Section: Nomenclature-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal

2015

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“…Considerable effort has been devoted to understanding the nature of labyrinth seal flows as evidenced by Sneck (1980). The focus of these efforts has most often been directed toward determination of leakage characteristics and accurate prediction methods.…”

Section: Introductionmentioning

confidence: 99%

Power Dissipation in Smooth and Honeycomb Labyrinth Seals

McGreehan¹,

1989

Volume 1: Turbomachinery

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The surface frictional characteristics of a labyrinth seal can result in significant windage power dissipation for high speed seals. Recent advances in seal design have produced high speed, high pressure labyrinth seals which operate at very low leakage rates. The reduced leakage is beneficial to gas turbine efficiency, but seal discharge temperatures can approach material design limits with high windage power dissipation. Also, a high air temperature rise can influence seal leakage flow. Consequently, the general assumption of negligible rotational effect on leakage is not always valid. A method is presented for the prediction of seal power dissipation and leakage flow over a wide range of design parameters. Results are compared to available test data and several approaches examined for the reduction of seal windage.

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“…The labyrinth seal has found application in steam turbines since the initial development of such machines by C. A. Parsons in the late 19th century [4]. Labyrinth seals remain popular to …”

Section: Introductionmentioning

confidence: 99%

Demonstration of a Dynamic Clearance Seal in a Rotating Test Facility

Messenger

Williams

Ingram

et al. 2017

Volume 8: Microturbines, Turbochargers and Small Turbomachines; Steam Turbines

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTThe successful demonstration of the "Aerostatic Seal" in a half scale rotating facility is described in this paper. The Aerostatic seal is a novel dynamic clearance seal specifically designed for steam turbine secondary gas path applications. The seal responds to radial rotor excursions, so a reduced clearance can be maintained compared to conventional labyrinth seal without damage to the seal. This enables increased turbine performance through reduced leakage and increased tolerance of turbine transient events typically found during start up. The seal is an extension of the existing retractable seal design already deployed in commercial steam turbines.The seal was tested in the Durham Rotating Seals Rig, which was developed specifically to test this device. The rig featured a rotor designed to run with large eccentricities to model high speed radial rotor excursions, and the seal was instrumented to measure the real time seal response to the rotor.The experimental campaign has conclusively demonstrated the ability of the seal to dynamically respond to the rotor position. The key result is that the seal is able to track the rotor position at high speed, and hence maintain a mean seal clearance that is lower than the rotor eccentricity. Overall this work marks a key milestone in the development of the Aerostatic Seal, and leads the way to testing in a steam environment and application in steam turbine plant. * Address all correspondence to this author. NOMENCLATURE INTRODUCTIONIn recent years an increased level of intermittent generation on the electrical grid has resulted in the requirement for conventional generators to operate more flexibly to meet electrical demand and remain profitable. For a steam turbine, flexibility in operation requires faster load changes, in turn leading to frequent transient radial rotor excursions and thermal expansions. Seals can then become damaged, reducing turbine efficiency and output power. A dynamic seal, which is a seal that can respond to the position of the rotor surface, offers major advantages over the conventional labyrinth seal. Not only can they accommodate rotor excursions, but they can operate at lower clearance, reducing leakage and hence increasing turbine efficiency. The "Aerostatic Seal", shown in Fig. 1, is a dynamic seal concept that is tested in this paper.The Aerostatic Seal is a development of the retractable seal used in steam turbines for a number of years. The seal is made up from a number of circumferential seal segmen...

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Labyrinth Seal Literature Survey

Abstract: A survey of the important published papers pertaining to labyrinth seals. A discussion of the present state-of-the-art of labyrinth seal theory and design from a thermodynamic and fluid mechanic viewpoint.

Cited by 21 publications

References 0 publications

Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal

Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal

Power Dissipation in Smooth and Honeycomb Labyrinth Seals

Demonstration of a Dynamic Clearance Seal in a Rotating Test Facility

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