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RISS 인기검색어
- 검색키워드
- 저자 : Fortes-Patella (검색결과 4 건)
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Numerical Methodology to Predict and Analyze Cavitating Flows in a Kaplan Turbine
Flavia Turi,Regiane Fortes-Patella,Guillaume Balarac 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.4
A computational methodology to predict the cavitation phenomena appearance and evolution in a 5-blades Kaplan turbine scale model was developed. Two different inlet boundary conditions have been tested in both non-cavitating and cavitating regimes: the classical one, the mass flow rate and the new one, the total pressure. The best results were obtained applying a constant total pressure on the inlet. The torque and efficiency drop curves were well-predicted with the proposed calculation methodology and the numerical cavitation structures agreed with experimental observations. Indeed, this new inlet boundary condition allows to keep the machine head constant during the cavitation drop, as in experiments. Unsteady simulations are under investigation to improve the prediction and the analyses of more developed cavitating regimes.
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Experimental and Numerical Investigation of the Erosive Potential of a Leading Edge Cavity
Jean-Bastien Carrat,Regiane Fortes-Patella,Jean-Pierre Franc 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.2
This paper presents a joint experimental and numerical analysis of the erosive potential of an unsteady cavity that develops at the leading edge of a two-dimensional hydrofoil and periodically sheds vapour clouds. From an experimental viewpoint, the erosive potential was characterized by pressure pulse height spectra. The hydrofoil was equipped with eight pressure sensors made of PVDF piezoelectric film that allowed the measurement of flow aggressiveness at different locations along the hydrofoil chord. It was shown that the mean peak rate over a large number of cavity pulsations exhibits a maximum at a distance from the leading edge close to the maximum cavity length. Moreover, the increase in flow aggressiveness caused by an increase in flow velocity can be explained by an increase in both amplitude and frequency of impact loads. From a numerical viewpoint, the unsteady Reynolds averaged Navier-Stokes (RANS) equations were solved using a modified k-ε RNG turbulence model together with a homogeneous cavitation model within a two-dimensional approach. Flow aggressiveness was estimated from the Lagrangian derivative of the computed void fraction that allows identifying the regions of collapse of vapour structures. Three different critical regions from an erosive viewpoint were numerically identified. Apart from the region of collapse of the shed cloud (which was not instrumented in the present study), the computations showed a maximum of aggressiveness around the maximum cavity length as found experimentally. Another region of high aggressiveness closer to the leading edge and associated to the upward movement of the re-entrant jet was predicted by the present numerical model but not confirmed experimentally, which probably shows the limitation of a two-dimensional approach.
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Numerical Cavitation Intensity on a Hydrofoil for 3D Homogeneous Unsteady Viscous Flows
Leclercq, Christophe,Archer, Antoine,Fortes-Patella, Regiane,Cerru, Fabien Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.3
The cavitation erosion remains an industrial issue for many applications. This paper deals with the cavitation intensity, which can be described as the fluid mechanical loading leading to cavitation damage. The estimation of this quantity is a challenging problem both in terms of modeling the cavitating flow and predicting the erosion due to cavitation. For this purpose, a numerical methodology was proposed to estimate cavitation intensity from 3D unsteady cavitating flow simulations. CFD calculations were carried out using Code_Saturne, which enables U-RANS equations resolution for a homogeneous fluid mixture using the Merkle's model, coupled to a $k-{\varepsilon}$ turbulence model with the Reboud's correction. A post-process cavitation intensity prediction model was developed based on pressure and void fraction derivatives. This model is applied on a flow around a hydrofoil using different physical (inlet velocities) and numerical (meshes and time steps) parameters. The article presents the cavitation intensity model as well as the comparison of this model with experimental results. The numerical predictions of cavitation damage are in good agreement with experimental results obtained by pitting test.
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Numerical Cavitation Intensity on a Hydrofoil for 3D Homogeneous Unsteady Viscous Flows
Christophe Leclercq,Antoine Archer,Regiane Fortes-Patella,Fabien Cerru 한국유체기계학회 2017 International journal of fluid machinery and syste Vol.10 No.3
The cavitation erosion remains an industrial issue for many applications. This paper deals with the cavitation intensity, which can be described as the fluid mechanical loading leading to cavitation damage. The estimation of this quantity is a challenging problem both in terms of modeling the cavitating flow and predicting the erosion due to cavitation. For this purpose, a numerical methodology was proposed to estimate cavitation intensity from 3D unsteady cavitating flow simulations. CFD calculations were carried out using Code_Saturne, which enables U-RANS equations resolution for a homogeneous fluid mixture using the Merkle"s model, coupled to a - turbulence model with the Reboud"s correction. A post-process cavitation intensity prediction model was developed based on pressure and void fraction derivatives. This model is applied on a flow around a hydrofoil using different physical (inlet velocities) and numerical (meshes and time steps) parameters. The article presents the cavitation intensity model as well as the comparison of this model with experimental results. The numerical predictions of cavitation damage are in good agreement with experimental results obtained by pitting test.
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