Numerical simulation on characteristics of hot and cold fluids mixed in tee junctions of different structures
HOU Cong;WANG Hexu;ZHANG Fangju;JIANG Yanlong;College of Aerospace Engineering,Nanjing University of Aeronautics and Astronautics;
As to the issue that the thermal fatigue of pipe could be induced by the thermal fluctuation caused by hot and cold fluids mixed in tee junctions, the effect of different structures on the characteristics of hot and cold fluids mixed in tee junctions is studied. The Large Eddy Simulation( LES)method is used to numerically simulate the tee junction models of different diameter ratios and different angles of branch pipe. The results show that,a vortex in the downstream of branch flow is formed because the branch flow is changed by the oppression of main flow,which leads to the thermal fluctuation of upper pipe wall is more significant than that of bottom pipe wall; when the diameter ratio increases,the effective area of main pipe flow under the vortex gets smaller,the thermal fluctuation of mixed hot and cold fluids weakens,and the distance of the mixed area increases; when the angle of branch pipe decreases,the vortex disappears gradually,the thermal fluctuation of mixed hot and cold fluids weakens,and the distance of mixing area increases as well.