Study on flow phenomena to prevent thermal fatigue at T-junction pipe

Abstract

Thermal fatigue cracking may initiate at a tee pipe where high and low temperature fluids flow in. The mixing flow causes temperature fluctuation near the pipe wall and may result in fatigue crack initiation. In this study, flow pattern at the mixing tee pipe was investigated by experiments in order to prevent the thermal fatigue. Visualization of flow was conducted by a test section of transparent acrylic resin and a tracer method. The test section is consisted of a horizontal main pipe with an inner diameter of 60, 150 mm and a vertical branch pipe with an inner diameter of 20, 30, 50 mm. Visualization tests showed flow in the main pipe penetrated into the branch pipe intermittently in some cases. The penetration patterns were categorized by the momentum ration for the flows in the main and branch pipes. The maximum penetration depth correlated with the momentum ration.