Conjugate numerical simulation of wall temperature fluctuation at a T-junction pipe

Abstract

Thermal fatigue cracks may occur in a T-junction pipe due to the mixing of hot and cold fluids. To develop an evaluation method for thermal fatigue, the authors previously performed a mixing tee experiment called the T-Cubic experiment. In this study, a fluid-structure coupled simulation for conjugate heat transfer was carried out to investigate the predictive performance of the flow and temperature fields and temperature fluctuation on the pipe inner surface at a mixing tee of the T-Cubic experiment. The computational domain included 304 type stainless steel pipe as well as the working fluid of water. Time-averaged velocity and temperature were reproduced well over the entire computational domain. Although velocity fluctuation intensity at a distance from the wall was relatively smaller than experimental data, the simulation could reproduce the trend of the experimental data, especially the velocity fluctuation intensity peak near the wall. The temperature fluctuation intensity was also larger than the experimental data, though the tendency could be reproduced by the simulation. The temperature fluctuation intensity on the pipe inner surface is the most important parameter for thermal fatigue and though it was 20% to 36% larger than the experimental data at its peak, the tendency was reproduced to a certain extent. The fluid temperature in the numerical simulation fluctuated at almost the same level from 0.1 Hz to 10 Hz, but high frequency components attenuated and low frequency components around 0.1 Hz remained on the pipe inner surface.

Keywords

• thermal fatigue
• t-junction pipe
• heat transfer
• temperature fluctuation
• numerical simulation
• large eddy simulation