THERMAL STRIPING TEMPERATURE-FLUCTUATION ANALYSIS USING THE ALGEBRAIC STRESS TURBULENCE MODEL IN WATER AND SODIUM

A three-dimensional temperature fluctuation analysis was carried out using a general-purpose multidimensional thermohydraulic analysis code for a 1 : 2 scale model water experiment and a 1 : 1 scale model sodium experiment simulating thermal striping phenomena. The code was incorporated with an algebraic stress turbulence model (ASM) and an adaptive control system based on the fuzzy theory to control time step sizes. Calculational results under the test conditions of various flow velocity ratios showed good agreement with the measured intensity distribution and maximum value of the temperature fluctuations. From the analysis, it was concluded that ( 1 ) the ASM is applicable to the intensity evaluation of the temperature fluctuations related to the thermal striping phenomena, ( 2) a combined approach of the ASM and the higher-order accurate schemes such as the quadratic upstream interpolation for convective kinematics (QUICK) and QUICK with the filtering remedy and methodology (FRAM) is recommended to analyze overall turbulent flow and temperature fields in engineering applications, and ( 3 ) the adaptive time step size control system is practical in reducing computing efforts.