Experiments and two different turbulence models comparisons on thermal mixing phenomenon in a tee piping

摘要

Thermal fatigue failures in reactor cooling systems of nuclear power plants are caused by the fluctuating stresses on a piping system due to the hot and cold flows are mixed together in a mixing piping. The present paper describes BSL Reynolds Stress (BSL-RSM) and k-epsilon (k-ε) simulation data of thermal mixing in a mixing piping compared with results from experimental data. The fluid in the experiment is concentration of de-ionized water and the liquid electrical conductivities are measured by the use of the 16x16 electrode. To verify the mixing phenomenon between electrical conductivity of de-ionized water and temperature of water, the inlet temperatures of the hot and cold water in the simulation process are set to 80°C and 15°C separately. The analytic results calculated by the commercial CFD code ANSYS CFX 11.0 show that the different turbulence model ( BSL-RSM, k-ε ) and different turbulent Prandtl number ( 0.9, 0.2, 0.1) will affect the simulation results of temperature fluctuations. 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. For smaller turbulent Prandtl number, the perditions are in good agreement with measurements.