Numerical simulation on turbulent flow and heat transfer of the square cross-section helical duct

A three-dimensional model was established to investigate the flow and heat transfer of square helical duct in which constant heat flux were specified in the inside wall and the turbulent flow at Re=28628 was considered. As a result, it was found that the area of turbulent region was larger at import region. Then, the centre of turbulent region closed to the inner wall. Meanwhile, the largest axial velocity was near the external wall. The turbulent intensity and the Nu number changed to stabilize after the spiral angle of 450°. In the cross-section, the emergence of multiple secondary flows enhanced the asymmetry of flow and heat transfer.