Influence of Secondary Flow Generated in a 90-deg Bend on the Thermal-Hydraulic Characteristics in a Mixing Tee

• Published in: Nuclear science and engineering 2008-02, Vol.158 (2), p.194-202
• Main Authors: Yuki, Kazuhisa, Sugawara, Yoshimasa, Hosseini, Seyed Mohammad, Hashizume, Hidetoshi, Toda, Saburo, Tanaka, Masa-aki, Muramatsu, Toshiharu
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Installations for energy generation and conversion: thermal and electrical energy
• ISSN: 0029-5639; 1943-748X
• DOI: 10.13182/NSE08-A2746

This study aims at clarifying a relationship between nonisothermal fluid mixing in a T-junction area with a 90-deg bend upstream and temperature fluctuations induced by the unstable mixing, by visualizing the flow fields with particle image velocimetry and measuring fluid-temperature fluctuation in the vicinity of a wall. From the visualization, it is clarified that a high-temperature jet flowing out from a branch pipe swings and sways near the wall, though the mixing patterns are basically classified into the same ones without the 90-deg bend upstream. Furthermore, there are cautionary conditions in which the temperature fluctuation is maximized in a transition regime between a stratified flow and a turn-jet flow. It seems that the principal cause is repetitional generation and disappearance of a circulating flow formed behind the jet due to an interaction between unsteady behavior of a secondary flow in a decay process after the bend and the wakes formed behind the jet, which leads to the vigorous oscillation of the jet near the wall.