Fluid Flow and Heat Transfer in Two-Pass Smooth Rectangular Channels With Different Turn Clearances

Abstract

Flow characteristics in stationary two-pass channels with a sharp 180-deg turn have been measured using LDV (laser Doppler velocimeter), directing special attention to the influence of the size of the turn clearance on the flow structure. The main features of the flow, flow separation and recirculation, secondary flow, turbulence intensities, measured with Re=3.5×104 for three turn clearances, are presented. A close comparison of the velocity data with local Sherwood number distributions on the channel walls reveals that the wall-normal velocity mainly dominates the heat transfer in the channel, but the wall-parallel component also contributes locally to heat transfer after the turn.