A-priori study of subgrid-scale models for the flow field in the rotor exit region of a centrifugal turbomachine

Akbari, Ghasem; Montazerin, Nader

doi:10.1016/j.ijheatmasstransfer.2013.06.076

Cited by 9 publications

(36 citation statements)

References 37 publications

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“…This non-dimensional quantity interprets as the ratio of particle response time and the Kolmogorov time scale of flow. The Stokes number of the present data was calculated to be 2 × 10 −5 that indicates a negligible particle lag effect and proper choice of seeding particles [2]. The pixelbased uncertainty for displacement estimation is evaluated to be 1.25% for a 32 × 32 pixel interrogation area.…”

Section: Uncertainty Analysismentioning

confidence: 91%

“…The spatial resolution of PIV is selected to be 1 mm which is roughly 18 times larger than the estimated Kolmogorov length scale ( 57 μm ) for the present flow field [30]. According to these characteristics and configuration of camera, the dimensions of each rectangular FOV are calculated to be 100 × 74 mm 2 .…”

Section: Spiv Setup and Data Acquisition Processmentioning

confidence: 99%

“…=̄; (2) =̄2 − 1 3 tr ̄2 ; (3) =̄2 − 1 3 tr ̄2 ; (4) =̄̄−̄̄; (5) =̄2̄−̄̄2; (6) =̄̄2 −̄2̄− 2 3 tr ̄̄2 ; (7) =̄̄̄2 −̄2̄̄; (8) =̄̄̄2 −̄2̄̄; (9) =̄2̄2 +̄2̄2 − 2 3 tr ̄2̄2 ; (10)…”

Section: Predictor Tensors For Sgs Modelmentioning

confidence: 99%

“…The models performance has been desirable in classic flows when consistent assumptions are considered. However, deviation of model prediction is considerable in vortical anisotropic flows or complex geometries [2][3][4]. For instance, the Smagorinsky model is an eddy-viscosity model and relates the subgrid-scale (SGS) stress tensor to the strain rate tensor.…”

Section: Introductionmentioning

confidence: 99%

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Subgrid-scale stress parameterization for anisotropic turbomachinery flow as deduced from stereoscopic particle image velocimetry measurements

Akbari

Montazerin

2019

J Braz. Soc. Mech. Sci. Eng.

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The present study searches for parametric subgrid-scale models for the turbomachinery flow based on single-plane stereoscopic particle image velocimetry measurements. A group of deformation tensors are used as the predictors to parameterize the subgrid-scale stress tensor as the response. Missing terms in the rotation rate tensor are completed with a novel approach which is based on geometrical relations between deformation and subgrid-scale tensors. The optimal relations for parametric subgrid-scale models are shaped after minimizing the square of error between modeled and real SGS stresses. The most superior and inferior one-predictor models are based on strain rate and rotation rate tensors, respectively. The two-predictor models show the most efficient prediction of subgrid-scale stress where the correlation coefficient is up to 43% larger than that of the classical Smagorinsky model. The three-to five-predictor models are inefficient since they give minor enhancement of correlation coefficient with a considerably larger computational cost.

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Section: Uncertainty Analysismentioning

confidence: 91%

Section: Spiv Setup and Data Acquisition Processmentioning

confidence: 99%

Section: Predictor Tensors For Sgs Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Subgrid-scale stress parameterization for anisotropic turbomachinery flow as deduced from stereoscopic particle image velocimetry measurements

Akbari

Montazerin

2019

J Braz. Soc. Mech. Sci. Eng.

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“…(4)(5)(6)(7). Note that the non-dimensional distance is chosen to be the closest wall from the grid point.…”

Section: Large-eddy Simulationmentioning

confidence: 99%

Flow Field Velocity Measurement Around a Horizontal-Axis Wind Turbine

Amano

Shen

2014

52nd Aerospace Sciences Meeting

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A basic understanding of flow characteristics over near wall region is essential to a complete study of Aerodynamics. In this study, a low turbulence, subsonic wind tunnel is used to perform the air flow velocity measurement, which are used to validate the LargeEddy Simulation (LES) code for predictions of a wind turbine flow behavior. Hotwire probe is the tool to process the measurement of air flow velocity through the test section. The experimental results of inlet air flow velocities provide boundary conditions for Computational Fluid Dynamics(CFD) simulations. The velocity map at the middle plane of test section is obtained from both experiment work and CFD simulation. The CFD methods show a good agreement for the near wall region velocity profile. Nomenclature A + = non-dimensional distance for the dumping function of Smagorinsky model C s = Smagorinsky constant ds = smallest cell size in Ansys meshing dl = largest cell size in Ansys meshing f s = dumping function H = characteristic length j = the number of grid points from the bottom wall in y direction k = Geometric growth ratio in Ansys meshing NY= the total number of grid points in y direction r = bias factor in Ansys meshing Re τ = friction Reynolds number S ij = strain rate tensor U( ) = relative uncertainty of temperature U( ) = relative uncertainty of calibrator u m = friction velocity u 1 , u 2 = the velocity of the first grid point (u 1 ), and second grid point (u 2 ) u + = non-dimensional velocity ( ⁄ ) u τ = friction velocity x,y,z = coordinate directions (x:spanwise direction, y:height direction z:flow direction) x 1 , y 1 = the distance from the wall to the first grid point y j = grid points number from the bottom wall y 2 = the distance from the wall to the second grid point y + ,x + = non-dimensional distance from the wall ( ⁄ ⁄ symbols Δ = filterling width 2 ΔT = Temperature difference = thickness of boundary layer ν = kinematic viscosity ν SGS = SGS eddy viscosity τ w = wall shear stress

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Contribution of jet–wake–volute interactions to flow characteristics and turbulence models

Montazerin¹,

Akbari²,

Mahmoodi³

2015

Developments in Turbomachinery Flow

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A-priori study of subgrid-scale models for the flow field in the rotor exit region of a centrifugal turbomachine

Cited by 9 publications

References 37 publications

Subgrid-scale stress parameterization for anisotropic turbomachinery flow as deduced from stereoscopic particle image velocimetry measurements

Subgrid-scale stress parameterization for anisotropic turbomachinery flow as deduced from stereoscopic particle image velocimetry measurements

Flow Field Velocity Measurement Around a Horizontal-Axis Wind Turbine

Contribution of jet–wake–volute interactions to flow characteristics and turbulence models

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