Experimental study on thermal mixing related to eddy structure in T-junction

This paper deals with the experimental investigation of thermal striping phenomena in a T-junction piping system as the typical part where influential temperature fluctuation in structural integrity may be induced by the thermal mixing. In this study, a simplified T-junction piping system consisting of a rectangular duct for main stream and a circular pipe for branch stream was used as the test section in the water experiment. Time series of instantaneous pictures in two-dimensional velocity vector field were obtained by PIV (Particle Image Velocimetry) technique in the mixing area. And fluid temperature fluctuations at several positions at 2 mm inside from the wall were also measured by thermo-couples. Focusing on the frequency characteristics, formation of eddy structure in the mixing area and mutual relation between the temperature fluctuation generation and the flow structure were discussed. (author)