Effect of curvature ratio on thermal mixing characteristics in a T-junction area which has a 90-degree bend in the upstream area

Thermal mixing characteristics in a T-junction area which has different type of 90-degree bend in the upstream area are evaluated in order to clarify the effect of the curvature ratio on the fluid mixing and wall-temperature fluctuation. The fluid mixing states at some velocity ratios are visualized with PIV measuring system first and its characteristics are associated with the temperature fluctuation data in the vicinity of wall measured with thin thermocouples. It is clarified that the curvature ratio of 90-degree bend strongly affects the thermofluid mixing state, and different effects on the temperature fluctuation depending on the curvature ratio are confirmed. Especially, there is a possibility that the low curvature ratio of bend, in which a separation occurs, is useful for the control of the wall temperature fluctuation due to the strong turbulent mixing effect.