T字合流部の逆流現象による熱疲労評価手法の検討

（上流外乱が流体温度変動特性に与える影響）

抄録

Thermal fatigue cracking may initiate at a tee pipe where high and low temperature fluids flow in. In this study, the penetration depth and fluid temperature fluctuations in a branch pipe of a mixing tee were investigated under flow patterns where the main pipe flow impinges on the branch pipe wall and penetrates into the branch pipe. The test section consists of a horizontal main pipe with an inner diameter of 150 mm and a vertical branch pipe with an inner diameter of 50 mm. A 45° elbow was installed at the upstream position on the branch pipe side in order to study the effect on the penetration depth and temperature fluctuations. Fluid temperature distribution along the branch pipe was measured with eight sheathed thermocouples. The maximum penetration depth into the branch pipe increased when the upstream elbow was installed on the branch pipe side. The fluid temperature fluctuations also increased, especially in the range of relatively small momentum ratios where the hot mainstream intermittently penetrated into the branch pipe.