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Effects of geometric parameters of a staggered labyrinth seal on leakage flow

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Abstract

Staggered labyrinth seals are used in gas turbines for cooling turbine blades. In this study, numerical analyses were performed to evaluate the discharge coefficients about the shape variables of staggered labyrinth seals. Four shape variables were considered: cavity width (CW), staggered height (GH), staggered width (GW), and staggered position (GP). Changes in the discharge coefficient with the shape variables were analyzed. Strategies were investigated to decrease the discharge coefficient of a staggered labyrinth seal. The discharge coefficient of the optimized staggered labyrinth seal was 37 % smaller than that of a straight labyrinth seal. We hypothesized that the size of the vena contracta and acceleration in the axial direction were related to the discharge coefficient. However, an association between only the GW was not observed. The wall shear stress was sensitive only to the GH and independent of the other shape parameters.

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Abbreviations

A c :

Cross-sectional area of labyrinth seal [m2]

AVN :

Normalized axial velocity \({\rm{AVN}} = {{{\rm{local}}\,{\rm{axial}}\,{\rm{velocity}}} \over {{\rm{average}}\,{\rm{axial}}\,{\rm{velocity}}}}\)

C d :

Discharge coefficient

C n :

Normalized clearance \({{\rm{C}}_{\rm{n}}} = {\xi \over {{\rm{clearance}}}}\)

C p :

Specific heat

CW ⋆ :

Normalized cavity width CW⋆ = CW/C

GH ⋆ :

Normalized staggered height GH⋆ = GH/C

GW ⋆ :

Normalized staggered width GW⋆ = GW/C

GP ⋆ :

Normalized staggered position GP⋆ = GP/(CW+0.5W)

k :

Turbulence kinetic energy [m2/s2]

ṁ :

Mass flow rate [kg/s]

P :

Pressure [Pa]

R :

Specific gas constant

T :

Temperature [K]

u :

Flow velocity [m/s]

u’:

RMS of the turbulent velocity fluctuations [m/s]

ρ :

Density [kg/m3]

γ :

Isentropic coefficient

ξ :

Coordinate from tooth tip

Id :

Ideal

In :

Inlet

Out :

Outlet

⋆:

Normalized

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Acknowledgments

This work was supported by an Agency for Defense Development Grant funded by the Korean Government (UD220004JD).

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Authors and Affiliations

  1. Department of Mechanical Engineering, Graduate School, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul, 02707, Korea

    Ye Hwan Chun

  2. School of Mechanical Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul, 02707, Korea

    Joon Ahn

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  1. Ye Hwan Chun
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Correspondence to Joon Ahn.

Additional information

Ye Hwan Chun received his B.S. in Mechanical Engineering from National Hanbat University in 2021. He is currently a Master’s student in Mechanical Engineering at Kookmin University. His research interests include optimal design of fluid machinery.

Joon Ahn is received his B.S. (1997), M.S. (1999), and Ph.D. (2003) from Seoul National University, Korea. He worked as a Senior Researcher at KIER (2006–2010) and is now a Professor at Kookmin University. His research interests include heat transfer and combustion problems in energy systems.

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Chun, Y.H., Ahn, J. Effects of geometric parameters of a staggered labyrinth seal on leakage flow. J Mech Sci Technol 37, 2959–2968 (2023). https://doi.org/10.1007/s12206-023-0522-6

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  • DOI: https://doi.org/10.1007/s12206-023-0522-6

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