A232 下向き閉塞分岐配管に生じる流動現象に関する研究 : 侵入深さの変動メカニズム(OS2 保全・設備診断技術(5))

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Hot water in a main pipe flows into a branch pipe and forms a thermally stratified layer with cold water at a bent section. Fluctuation of the thermally stratified layer may initiates thermal fatigue crack in the branch pipe. It has been reported that the fluctuation of penetration depth induced by the main flow in the branch pipe with a closed end was caused by generation of a large swirl flow at L = 4D_b. Experiments with the rectangular and reduced branch pipes were conducted to suppress the fluctuation of penetration depth induced by the main flow. It was shown that the fluctuation of penetration depth in the rectangular pipe was suppressed, because the large swirl flow at L = 4D_b was not formed. It was also shown that the rectangular and reduced branch pipes were available to decrease the penetration depth by the main flow in the branch pipe.