Abstract:

Three-dimensional turbulent forced convective heat transfer and its flow characteristics in a helical rectangular duct are simulated using a shear stress transport (SST) k-ω turbulence model and taking into consideration the modified low Reynolds number near the wall. The temperature,flow field and the streamline at different axial locations along the stream are analyzed for different Reynolds numbers, different curvatures and different torsions. The causes of the differences between the inner and outer walls of the helical rectangular ducts are discussed and the differences between the helical duct and straight channel are compared. A second flow in the helical duct caused by the centrifugal effect results in the differences between the inner and outer walls. For the present study, the flow is steady after the first roll. The Reynolds number can enhance the overall heat transfer, and torsion and curvature do not much change the heat transfer effect. But the rectangular configurations can significantly enhance the heat transfer coefficients. The results obtained from the present investigation are meant to serve as basic data for further cooling design using helical rectangular ducts.

Key words: helical duct, turbulence, curvature, heat transfer, rectangular