Fully Developed Turbulent Flow in a Curved Rectangular Duct

Abstract

Fully developed flows in a curved rectangular duct having a breadth/curvature-radius ratio of 0.25 are studied experimentally. A flow-turning angle of more than 150° is required for the flow to reach a fully developed state in any duct which has an aspect ratio (height/breadth) of the cross section ranging from 0.4 to 16. In the case of low aspect ratios, the main flow has a forced vortex-type velocity distribution, and has a free vortex-type distribution at high aspect ratios. Concerning the skewed boundary layer on the end plate, similarity exists in the secondary flow velocity distributions. It was found that the profile of the distribution is the same as one of two-dimentional wall jets, and that the thickness of the secondary flow boundary layer should be considered separately from that of the main flow.