Rotation correction of wall function and velocity structure under the couple effects of buoyancy force and rotating effects at the entry section of the smooth straight channel

Abstract

Abstract This paper studies the effect of rotation on the turbulent boundary-layer flow in a rotating duct with a square cross section by using hot-wire. The experiments were conducted with the Reynolds numbers, based on the duct s hydraulic diameter (D\u202f=\u202f80\u202fmm) equaling 19,000. The rotation numbers (Ro) studied ranged from 0 to 0.362. Hot-wire measurements of the flow field were made at four cross sections of the rotating duct. The effects of rotation on velocity profile, semi-logarithmic mean velocity profile, and wall shear stress are discussed in this paper. Results obtained show the velocity deficit about the leading surface of the rotating duct, created by the secondary flows induced by the Coriolis force, to not increase monotonically with the increase in the Rotation number. Results obtained also show the effects of rotation to penetrate into the logarithm region, and the flow near the leading surface tends to laminarize. In this study, a correction factor is developed for logarithmic law to account for the effects of rotation, which can be used in CFD studies of rotating ducts that use wall functions.