Abstract
The fluctuating stresses on a piping system in reactor cooling systems of nuclear power plants are potential causes of thermal fatigue failures. These stresses are generated due to temperature fluctuations in regions where hot and cold flows are intensively mixed together. The main focus of this study shows that the application of eddy-viscosity (EVM) and Reynolds stress (RSM) turbulence models to solving flow and heat transfer in mixing piping. The present paper describes three Reynolds-Stress Models(BSL-RSM, ω-RSM, SSG-RSM)and three Eddy-Viscosity Models(SST, k-ε, k-ω) simulation data of temperature fluctuations in a mixing piping compared with results from experimental data proposed by the Laboratory for Nuclear Energy Systems, Institute for Energy Technology, ETHZ, Zurich, Switzerland. The experimental measurements ( concentration of de-ionized water)have been carried out by the use of the 16×16 electrode WMS on the basis of difference in liquid electrical conductivities. To verify the analogy between electrical conductivity of de-ionized water and temperature of water, the inlet temperatures of the hot and cold water are set to 80℃ and 15℃ separately in the simulation process. The computational results are in qualitative good agreement with experimental data and the correlation between electrical conductivity of de-ionized water and temperature of water is good. The purpose of this paper is to analyze which turbulent model is suit for the mixing phenomenon.
