LOCAL HEAT-TRANSFER IN A ROTATING 2-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 differen t cross section, a triangular duct. Unlike a square cross section, the triangular shape provides more restriction to the formation of the se condary flows. Moreover, the studied orientation of the right triangul ar duct avoids formation of symmetric vortex structures in the crossfl ow plane. This paper presents turbulent heal transfer characteristics of a two-pass smooth-walled triangular duct. One pass is for radial ou tward flow and the other for radial inward flow. With rotation the rad ial outward and inward flow directions show different surface heat tra nsfer characteristics. Like a square duct, differences between the tra iling and the lending Nusselt number ratios for the triangular duct in crease with rotation number. However, the rate of change of Nusselt nu mber ratios with rotation number varies for the two duct geometries. S tandard k - epsilon model predictions for a radial outward flow situat ion show that the Nusselt number ratio variations with Reynolds number are not drastic for the same rotation number.