Three-dimensional unsteady Navier—Stokes analysis of stator—rotor interaction in axial-flow turbines

He, L.

doi:10.1243/0957650001537813

Cited by 45 publications

(17 citation statements)

References 17 publications

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“…15 For the spatial discretization of the equations, a second-order central difference type of spatial discretization was previously adopted in the solver for evaluating the fluxes at the cell boundary faces. 15,16 Recently, a pressure-advective flux split upwinding discretization, AUSM (Liou 17 ) has been implemented. The upwind scheme is shown to produce less numerically dissipative results in near-wall viscous flow regions, as desired.…”

Section: Baseline Flow Solution Methodsmentioning

confidence: 99%

Multiscale block spectral solution for unsteady flows

2017

Numerical Methods in Fluids

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Summary Many problems of interest are characterized by 2 distinctive and disparate scales and a huge multiplicity of similar small‐scale elements. The corresponding scale‐dependent solvability manifests itself in the high gradient flow around each element needing a fine mesh locally and the similar flow patterns among all elements globally. In a block spectral approach making use of the scale‐dependent solvability, the global domain is decomposed into a large number of similar small blocks. The mesh‐pointwise block spectra will establish the block‐block variation, for which only a small set of blocks need to be solved with a fine mesh resolution. The solution can then be very efficiently obtained by coupling the local fine mesh solution and the global coarse mesh solution through a block spectral mapping. Previously, the block spectral method has only been developed for steady flows. The present work extends the methodology to unsteady flows of short temporal and spatial scales (eg, those due to self‐excited unsteady vortices and turbulence disturbances). A source term–based approach is adopted to facilitate a two‐way coupling in terms of time‐averaged flow solutions. The global coarse base mesh solution provides an appropriate environment and boundary condition to the local fine mesh blocks, while the local fine mesh solution provides the source terms (propagated through the block spectral mapping) to the global coarse mesh domain. The computational method will be presented with several numerical examples and sensitivity studies. The results consistently demonstrate the validity and potential of the proposed approach.

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Section: Baseline Flow Solution Methodsmentioning

confidence: 99%

Multiscale block spectral solution for unsteady flows

2017

Numerical Methods in Fluids

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“…In order to verify the validity of the solver, an appropriate combination of component validation and code-to-code comparisons has, therefore, been performed. The capability of the multi-row, multi-passage, baseline solver to predict the aerodynamic response to blade-row interaction and blade oscillation has been verified against experimental data in references [24] and [27], respectively. Furthermore, the single-passage methodology has been validated in an isolated row against a semi-analytical solution of Namba [28].…”

Section: Validation Of the Single Passage Solvermentioning

confidence: 93%

Influence of upstream stator on rotor flutter stability in a low pressure steam turbine stage

Huang

Bell³

2006

Proceedings of the Institution of Mechanical Engineers, Part A:

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Conventional blade flutter prediction is normally based on an isolated blade row model, however, little is known about the influence of adjacent blade rows. In this article, an investigation is presented into the influence of the upstream stator row on the aero-elastic stability of rotor blades in the last stage of a low pressure (LP) steam turbine. The influence of the upstream blade row is computed directly by a time-marching, unsteady, Navier -Stokes flow solver in a stator -rotor coupled computational domain. The three-dimensional flutter solution is obtained, with adequate mesh resolution, in a single passage domain through application of the Fourier-transform based Shape-Correction method. The capability of this single-passage method is examined through comparison with predictions obtained from a complete annulus model, and the results demonstrate a good level of accuracy, while achieving a speed up factor of 25. The present work shows that the upstream stator blade row can significantly change the aero-elastic behaviour of an LP steam turbine rotor. Caution is, therefore, advised when using an isolated blade row model for blade flutter prediction. The results presented also indicate that the intra-row interaction is of a strong three-dimensional nature.

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“…Local instantaneous information is transferred directly across the interface by a second-order interpolation and correction method. 26 …”

Section: Methodsmentioning

confidence: 99%

Stator conditioning effects on steam turbine rotating instability

Stüer

2014

Proceedings of the Institution of Mechanical Engineers, Part A:

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Rotating stall and rotating instability (as it is often called) have been extensively studied in compressors and fan stages. Though less known, they are relevant to steam turbines operated at very low mass flow conditions. In the present work, flow under various flow rate conditions in the last stage of steam turbine configurations is investigated. The objective of this study is to identify the main physical dependent parameters of rotating instability for turbine configurations and to see if they can be used to explore the potential of delaying rotating instability by blading design or by control. The computational results clearly show that the onset and development of the flow instability in the rotor row are subject to the intra-row gap distance and in particular can be influenced by the upstream stator flow conditioning. Further 3D calculations with a re-staggered stator row are carried out to examine the effect on a 3D steam turbine blading configuration. Under the flow conditions considered in this study, rotating instability is consistently shown to be suppressed for the 3D stage configuration with a re-staggered stator row, compared to the original configuration. The flow pattern responsible for this effect is also examined.

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Three-dimensional unsteady Navier—Stokes analysis of stator—rotor interaction in axial-flow turbines

Cited by 45 publications

References 17 publications

Multiscale block spectral solution for unsteady flows

Multiscale block spectral solution for unsteady flows

Influence of upstream stator on rotor flutter stability in a low pressure steam turbine stage

Stator conditioning effects on steam turbine rotating instability

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