Large Eddy Simulation of a High Reynolds Number Swirling Flow in a Conical Diffuser

Duprat, Cédric; Métais, Olivier; Laverne, Thomas

doi:10.5293/ijfms.2009.2.4.346

Cited by 2 publications

(1 citation statement)

References 8 publications

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“…2). Des termes de forcage sont ajoutés aux equations de Navier-Stokes pour conserver un débit et un taux de rotation constant [13]. Ainsi, une force axiale permet de compenser le frottementà la paroi et d'atteindre le débit fixé par l'utilisateur.…”

Section: Condition D'entréeunclassified

Simulation des grandes échelles d'un aspirateur de centrale hydraulique

Duprat

Balarac

Métais

et al. 2009

Mécanique & Industries

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Reçu le 20 avril 2009Résumé -La technique de simulation des grandeséchelles (SGE) est utilisée pour simuler l'écoulement dans un aspirateur de centrale hydrauliqueà différents points de fonctionnement. La complexité de la géométrie et le haut nombre de Reynolds de l'écoulement nécessitent l'utilisation de méthodes spécifiques. Ainsi, nous avons développé un traitementà la paroi tenant compteà la fois du frottement pariétal mais aussi du gradient de pression. La technique utilisée pour permettre de générer des conditions d'entrée instationnaires réalistes,à partir de données expérimentales, estégalement détaillée. Les différents régimes d'écoulements résultant de cette configuration sont alors présentés.

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Section: Condition D'entréeunclassified

Simulation des grandes échelles d'un aspirateur de centrale hydraulique

Duprat

Balarac

Métais

et al. 2009

Mécanique & Industries

Self Cite

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Influence of turbulent inlet conditions on the flow inside a bulb turbine draft tube using Large-Eddy Simulations

Véras

Balarac

Métais

et al. 2021

IOP Conf. Ser.: Earth Environ. Sci.

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The head losses inside the draft tube of a bulb turbine can represent an important portion of the total energy losses due to the low heads at which these machines operate. However, the complexity of the flow makes it a numerical challenge to simulate. Previous studies have shown that Large Eddy Simulations (LES) based on mean inlet conditions improve flow prediction inside the draft tube’s cone but diverge further downstream [4]. Moreover, uncertainties and the lack of detailed experimental data at the inlet have been identified as the main reason for these discrepancies and precise measurements close to the walls are necessary to correctly validate the numerical simulations [8, 4]. Thanks to detailed experimental measurements, the objective of this paper is to enhance the accuracy of previous results by performing LES computations to numerically simulate the flow inside the draft tube of a bulb turbine, and to investigate the influence of inlet conditions using an innovative approach. A two-criteria based mesh adaptation [14] along with an element-wise masking strategy is used to assure a good spatial discretization level while reducing the computational cost. Partial experimental data imposed at the inlet are often not sufficient to achieve a proper downstream flow prediction with a LES. The real challenge thus consists in the economical generation of proper mean and fluctuating inlet flow fields. We first show that a simple homogeneous and isotropic synthetic turbulence field added to the mean experimental profiles may improve the prediction of the downstream flow, but this is only achieved through empirical adjustments. Therefore, we also investigate the use of machine learning procedure to automatically generate proper inlet mean and fluctuating fields.

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Large Eddy Simulation of a High Reynolds Number Swirling Flow in a Conical Diffuser

Cited by 2 publications

References 8 publications

Simulation des grandes échelles d'un aspirateur de centrale hydraulique

Simulation des grandes échelles d'un aspirateur de centrale hydraulique

Influence of turbulent inlet conditions on the flow inside a bulb turbine draft tube using Large-Eddy Simulations

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