Local heat transfer in a rotating two-pass ribbed triangular duct with two model orientations

Abstract

The paper presents experimental heat transfer results in a two-pass triangular duct with ribbed walls. The ribs are placed orthogonal to the bulk flow direction. The rotation is perpendicular to the duct axis. The duct orientation is varied by turning it about its axis with respect to the rotational plane. A change in the duct orientation with respect to the rotating frame causes a change in the secondary flow vortex and turbulence distribution. Consequently, the heat transfer from the individual surfaces changes. The Nusselt number ratio profiles of the 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 with smooth rotating surfaces. Heat transfer from the rib roughened surfaces are modeled by a high-Reynolds number k—ɛ model and a wall function with sand-roughness. Predictions show different secondary flow vortex structures for two different model orientations.