High-Accuracy Analysis Methods of Fluid Temperature Fluctuations at T-Junctions for Thermal Fatigue Evaluation

Abstract

T-junctions are widely used for fluid mixing in nuclear power and process plants. Temperature fluctuations generated by the mixing of hot and cold fluids at a T-junction can cause thermal fatigue failure. The existing method for evaluating thermal fatigue leads to an over-conservative evaluation in part. CFD/FEM coupling analysis is a useful tool for the more rational evaluation of thermal fatigue. The present paper aims to verify another high-accuracy difference scheme used for simulating fluid temperature fluctuations at T-junctions for rational evaluation of thermal fatigue. In addition to the high-accuracy numerical methods presented in the previous paper, the TVD 2nd-order upwind difference scheme (2UD) is also used for the CFD analysis. In the present simulation, the TVD 2UD scheme is only applied to calculate the convective term of the energy equation to facilitate the comparison with the previous simulation. For comparison, the simulation conditions including the geometry of T-junction are the same as those in the experiments in the literature. The simulation results for distributions of time-averaged fluid temperature are very close to the experimental and previous simulation results. Especially, the predicted results of fluid temperature fluctuations of our concern also agree with the experimental and previous simulation results very well. The simulation results indicate that the TVD 2UD scheme is also a high-accuracy numerical method for the simulation of unsteady phenomena, along with the hybrid scheme.