LOCAL HEAT-TRANSFER IN A ROTATING 2-PASS RIBBED TRIANGULAR DUCT WITH 2 MODEL ORIENTATIONS

This paper presents experimental heat transfer results in a two-pass t riangular duct with ribbed walls. The ribs are placed orthogonal to th e bulk flow direction. The rotation is perpendicular to the duct axis. The duct orientation is Varied by turning it about its axis with resp ect to the rotational plane. A change in the duct orientation with res pect to the rotating frame causes a change in the secondary flow vorte x and turbulence distribution. Consequently, the heat transfer from th e individual surfaces changes. The Nusselt number ratio profiles of th e six surfaces of the two-pass rib-roughened triangular duct depend on the rotation number. However, heat transfer with ribbed surfaces show different characteristics in rotation number dependency from those wi th smooth rotating Surfaces. Heat transfer from the rib roughened surf aces are modeled by a high-Reynolds number k-epsilon model and a wall function with sand-roughness. Predictions show different secondary flo w vortex structures for two different model orientations.