T字合流部の逆流現象による熱疲労評価手法の検討

（流体および管内面温度測定実験）

抄録

Thermal fatigue cracking may initiate at a tee pipe where high and low temperature fluids flow in. The mixing flow causes temperature fluctuation at the pipe inner surface and may result in fatigue crack initiation. In this study, fluid temperature fluctuations in a branch pipe of 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 is consisted of a horizontal main pipe with an inner diameter of 150 mm and a vertical branch pipe with an inner diameter of 50 mm. Fluid temperature difference in the inlets was about 30°C. The ratio of momentum in the inlets for main and branch pipes was changed. Temperature distribution along the branch pipe was measured with three measurement blocks. Two sheathed thermocouples were installed in the block. It was allowed to measure the fluid temperature at 1 mm from the wall and the temperature at the pipe inner surface simultaneously. The temperatures at the fluid and pipe inner surface fluctuated, because the hot flow in the main pipe penetrated into the branch pipe. The temperature fluctuation for small momentum ratio conditions increased with the momentum ratio and decreased in the direction of branch pipe axis. The temperature fluctuation for large momentum ratio conditions was saturated and became constant in the direction of branch pipe axis.