Numerical simulation of swirling flow in complex hydroturbine draft tube using unsteady statistical turbulence models
Abstract
A numerical method is developed for carrying out unsteady Reynoldsaveraged NavierStokes (URANS) simulations and detachededdy simulations (DESs) in complex 3D geometries. The method is applied to simulate incompressible swirling flow in a typical hydroturbine draft tube, which consists of a strongly curved 90 degree elbow and two piers. The governing equations are solved with a secondorderaccurate, finitevolume, dualtimestepping artificial compressibility approach for a Reynolds number of 1.1 million on a mesh with 1.8 million nodes. The geometrical complexities of the draft tube are handled using domain decomposition with overset (chimera) grids. Numerical simulations show that unsteady statistical turbulence models can capture very complex 3D flow phenomena dominated by geometryinduced, largescale instabilities and unsteady coherent structures such as the onset of vortex breakdown and the formation of the unsteady rope vortex downstream of the turbine runner. Both URANS and DES appear to yield the general shape and magnitude of mean velocity profiles in reasonable agreement with measurements. Significant discrepancies among the DES and URANS predictions of the turbulence statistics are also observed in the straight downstream diffuser.
 Authors:
 University of Minnesota
 ORNL
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE Office of Energy Efficiency and Renewable Energy (EERE)
 OSTI Identifier:
 930779
 DOE Contract Number:
 DEAC0500OR22725
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Hydraulic Engineering; Journal Volume: 131; Journal Issue: 6
 Country of Publication:
 United States
 Language:
 English
 Subject:
 13 HYDRO ENERGY; HYDRAULIC TURBINES; TUBES; COMPUTERIZED SIMULATION; INCOMPRESSIBLE FLOW; VORTEX FLOW; NAVIERSTOKES EQUATIONS; FLOW MODELS; COMPRESSIBILITY; REYNOLDS NUMBER
Citation Formats
Paik, Joongcheol, Sotiropoulos, Fotis, and Sale, Michael J. Numerical simulation of swirling flow in complex hydroturbine draft tube using unsteady statistical turbulence models. United States: N. p., 2005.
Web. doi:10.1061/(ASCE)07339429(2005)131:6(441).
Paik, Joongcheol, Sotiropoulos, Fotis, & Sale, Michael J. Numerical simulation of swirling flow in complex hydroturbine draft tube using unsteady statistical turbulence models. United States. doi:10.1061/(ASCE)07339429(2005)131:6(441).
Paik, Joongcheol, Sotiropoulos, Fotis, and Sale, Michael J. 2005.
"Numerical simulation of swirling flow in complex hydroturbine draft tube using unsteady statistical turbulence models". United States.
doi:10.1061/(ASCE)07339429(2005)131:6(441).
@article{osti_930779,
title = {Numerical simulation of swirling flow in complex hydroturbine draft tube using unsteady statistical turbulence models},
author = {Paik, Joongcheol and Sotiropoulos, Fotis and Sale, Michael J},
abstractNote = {A numerical method is developed for carrying out unsteady Reynoldsaveraged NavierStokes (URANS) simulations and detachededdy simulations (DESs) in complex 3D geometries. The method is applied to simulate incompressible swirling flow in a typical hydroturbine draft tube, which consists of a strongly curved 90 degree elbow and two piers. The governing equations are solved with a secondorderaccurate, finitevolume, dualtimestepping artificial compressibility approach for a Reynolds number of 1.1 million on a mesh with 1.8 million nodes. The geometrical complexities of the draft tube are handled using domain decomposition with overset (chimera) grids. Numerical simulations show that unsteady statistical turbulence models can capture very complex 3D flow phenomena dominated by geometryinduced, largescale instabilities and unsteady coherent structures such as the onset of vortex breakdown and the formation of the unsteady rope vortex downstream of the turbine runner. Both URANS and DES appear to yield the general shape and magnitude of mean velocity profiles in reasonable agreement with measurements. Significant discrepancies among the DES and URANS predictions of the turbulence statistics are also observed in the straight downstream diffuser.},
doi = {10.1061/(ASCE)07339429(2005)131:6(441)},
journal = {Journal of Hydraulic Engineering},
number = 6,
volume = 131,
place = {United States},
year = 2005,
month = 6
}

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