Computational fluid-dynamics modeling of supersonic ejectors: Screening of turbulence modeling approaches

•The fluid dynamics in a supersonic ejector for refrigeration systems was studied.•Different turbulence modeling approaches were compared.•Different mesh sizes and near wall modeling approaches were compared.•A computational fluid dynamics model was validated. Ejector refrigeration has not been able...

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Bibliographic Details
Published in:Applied thermal engineering Vol. 117; pp. 122 - 144
Main Authors: Besagni, Giorgio, Inzoli, Fabio
Format: Journal Article
Language:English
Published: Oxford Elsevier Ltd 05.05.2017
Elsevier BV
Subjects:
CFD
Closures
Compressibility
Computational fluid dynamics
Computer simulation
Economic conditions
Ejection
Ejector refrigeration
Ejectors
Entrainment
Fluid dynamics
Fluid flow
Local flow
Markets
Mathematical models
Modeling
Numerical analysis
Numerical prediction
Pressure recovery
Refrigeration
Reynolds averaged Navier-Stokes method
Simulation
Static pressure
Stokes law (fluid mechanics)
Studies
Turbulence models
CFD
Ejector refrigeration
Computational fluid dynamics
Modeling
Turbulence models
ISSN:1359-4311, 1873-5606
Online Access:Get full text
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Summary:•The fluid dynamics in a supersonic ejector for refrigeration systems was studied.•Different turbulence modeling approaches were compared.•Different mesh sizes and near wall modeling approaches were compared.•A computational fluid dynamics model was validated. Ejector refrigeration has not been able to penetrate the market because of the low coefficient of performance and because of the high influence of ejector performance on the efficiency of the refrigeration system. Improving the performance of ejector refrigeration systems relies on the understanding of the fluid dynamic phenomena, which can be obtained through computational fluid-dynamics approaches. Unfortunately, no agreement has been reached yet on the closures for the turbulence modeling in the Reynolds Averaged Navier-Stokes (RANS) approach. This paper contributes to the existing discussion by presenting a numerical study of the turbulent compressible fluid in a supersonic ejector. Seven RANS turbulence closures have been compared and, in addition, the turbulence models were tested under different near-wall modeling options in order to investigate the wall treatment effect on the numerical results. The numerical results have been validated by literature data consisting in entrainment ratio and wall static pressure measurements, for different ejector geometries and operating conditions. As a result, the k-ω SST model shows better performance in terms of global and local flow phenomena predictions for the different ejector geometries and operating conditions: (a) on the global point of view, the entrainment ratio is well predicted with a maximum relative error equal to about 10%, (b) on the local point of view, the shock wave position, the pressure recovery and the wall static pressure values are well predicted. The results, taking into account previous numerical studies, suggest the use of the k-ω SST model to simulate ejector fluid dynamics.
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ISSN:1359-4311
1873-5606
DOI:10.1016/j.applthermaleng.2017.02.011