Assessing Turbulent Models for Flow Accelerated Corrosion Prediction in a 90-Degree Bend

Abstract

Flow accelerated corrosion (FAC), is still prevail in power plants piping components and is driven by variables in hydrodynamics, water chemistry and material composition groups. Amongst these factors, flow hydrodynamics play a major role as FAC is a corrosion process limited by wall mass transfer rates. Computational Fluid Dynamics (CFD) have been employed to calculate mass transfer coefficient for further FAC rate assessment. However, various turbulent models have been used in literatures. In this study, CFD calculations of mass transfer coefficient in 90-degree bend are performed with different turbulent models including , ,  and  at the Reynolds number ( ) of 90,000 and the Schmidt number ( ) of 2.53. ,  and  models yield similar flow behaviour, while the  shows the delay in the flow separation and double vortices development. The predicted mass transfer coefficients from the three models also agree with the experimental result. The  outperforms the others with the maximum relative error of 14%. Although the obtained mass transfer coefficient from  model shows good agreement with experimental results at the outlet part of the bend, high discrepancies exist at the inlet part.

Flow accelerated corrosion (FAC), is still prevail in power plants piping components and is driven by variables in hydrodynamics, water chemistry and material composition groups. Amongst these factors, flow hydrodynamics play a major role as FAC is a corrosion process limited by wall mass transfer rates. Computational Fluid Dynamics (CFD) have been employed to calculate mass transfer coefficient for further FAC rate assessment. However, various turbulent models have been used in literatures. In this study, CFD calculations of mass transfer coefficient in 90-degree bend are performed with different turbulent models including k-ε RNG, k-ω SST, Transition k-kl-ω and Transition SST at the Reynolds number (Re) of 90,000 and the Schmidt number (Sc) of 2.53. k-ε RNG, Transition k-kl-ω and Transition SST models yield similar flow behaviour, while the k-ω SST shows the delay in the flow separation and double vortices development. The predicted mass transfer coefficients from the three models also agree with the experimental result. The k-ε RNG outperforms the others with the maximum relative error of 14%. Although the obtained mass transfer coefficient from k-ω SST model shows good agreement with experimental results at the outlet part of the bend, high discrepancies exist at the inlet part.