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Abstract: Three-dimensional
leakage flow characteristics of the stepped labyrinth seal installed in
the diagram for steam turbines are investigated using the Navier-Stokes
solver. The finite volume method is used to discretize the Navier-Stokes
equation. The standard
κ-ε two
equations turbulence model is used to close the solving equations. The
second order upwind scheme and the first order upwind scheme are applied
to solve convection and diffusion terms respectively. The leakage flow
fields in the stepped labyrinth seal with different pressure ratios at
three different sealing knife numbers and the same axial distance are
studied. In addition, the discharge coefficient of each case is
calculated. The numerical simulated results show the leakage flow rate
increases with decrease of the sealing knife numbers at the same
pressure ratio. The discharge coefficient increases with increment of
the pressure ratio at the same sealing knife numbers. The
characteristics of three-dime- nsional complex flow fields in the
stepped labyrinth seal are also illustrated. The study supplies the
theoretical foundation and technical support for the optimization design
of the stepped labyrinth seal.
Key
words: Steam
turbine Stepped labyrinth seal Leakage flow Numerical simulation
CLC No: TH136
国家自然科学基金资助项目(50506023). Received 20050725,
received in revised form 20051210
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