Local Heat Transfer in a Rotating Two-Pass Triangular Duct With Smooth Walls

Earlier heat transfer studies with orthogonal rotation were conducted mostly on ducts of square cross section. This paper reports a different cross section, a triangular duct. Unlike a square cross section, the triangular shape provides more restriction to the formation of the secondary flows. Moreover, the studied orientation of the right triangular duct avoids formation of symmetric vortex structures in the crossflow plane. This paper presents turbulent heat transfer characteristics of a two-pass smooth-walled triangular duct. One pass is for radial outward flow and the other for radial inward flow. With rotation the radial outward and inward flow directions show different surface heat transfer characteristics. Like a square duct, differences between the trailing and the leading Nusselt number ratios for the triangular duct increase with rotation number. However, the rate of change of Nusselt number rations with rotation number varies for the two duct geometries. Standard k–ε model predictions for a radial outward flow situation show that the Nusselt number ratio variations with Reynolds number are not drastic for the same rotation number.