Control technique of high-cycle thermal fatigue at a mixing tee with a 90-degree bend upstream by changing its location

Ohara, Hiroshi*; Yuki, Kazuhisa*; Hoseini, S. M.*; Hashizume, Hidetoshi*; Tanaka, Masaaki  

When temperature fluctuation in mixing tee pipe is transported to the structure, it may lead high-cycle thermal fatigue in the structure. Therefore, it is important to control the high-cycle thermal fatigue. In a 90-degree bend located in upstream of the tee, an unsteady secondary flow arises. The secondary flow affects the fluid mixing in tee and the distance between the tee and the bend is one of the most important parameters to characterize the temperature fluctuation. The temperature fluctuation and the fluid mixing structure are investigated experimentally varied the distance between the tee and the bend. When the tee is located at the close to the bend, the fluid mixing area tends to shift to the inside of the bended pipe. And the temperature fluctuation intensity becomes lower and decays faster in the stream direction. Experimental results suggest that changing the distance between the tee and the bend is useful to control the high-cycle thermal fatigue.