Numerical study of thermal mixing phenomenon using partially averaged Navier-Stokes

• Published in: Nuclear engineering and design Vol. 408; p. 112321
• Main Authors: Bilal, Ashhar, Gao, Puzhen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2023
• Subjects: High cycle thermal fatigue; Partially averaged Navier-Stokes; T-junction; Thermal mixing; Partially averaged Navier-Stokes; T-junction; High cycle thermal fatigue; Thermal mixing
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2023.112321

Thermal mixing between cold and hot streams of fluids in a T-junction may lead to high-cycle thermal fatigue in nuclear power plant piping material. Temperature fluctuations near the wall surface are the main reason for this degradation. Computational Fluid Dynamics (CFD) using space and energy-resolving turbulence modeling paradigms can predict this transient behavior. In this study Partially averaged Navier-Stokes (PANS) turbulence method is used to simulate the Vattenfall T-junction test case. Two different values for the filter control parameter fk = 0.5 and fk = 0.25 are used. Calculations results for velocity and temperature fields are compared with Large Eddy Simulations (LES) and available experimental data. For fk = 0.5, time-averaged and root mean square (RMS) temperatures show lower values than the LES and experimental data. For fk = 0.25 both time-averaged and RMS temperature results are close to the LES and experimental values. The Power Spectral Density (PSD) of the temperature signal shows peaks in the case of both PANS-0.25 and LES in the range of 3 to 4 Hz, which is in line with the experimental results. It can be concluded that the PANS method has the capability to resolve temperature and velocity fields for thermal mixing phenomenon in T-junction pipes and can be used for the assessment of high-cycle thermal fatigue.