Turbulent Heat Transfer in a Pipe Flow with a Pair of Twisted Tapes

Abstract

The characteristics of turbulent flow and heat transfer have been experimentally investigated with a circular pipe in which a pair of twisted tapes were inserted as a promoter of convective and radiative heat transfer. The three-dimensional velocity and turbulence field, the friction factor, and the local heat transfer coefficient were measured. It was found that a secondary flow was induced by the present promoter, and the heat transfer was enhanced to about three times that of a smooth pipe. A marked increase of the local heat transfer coefficient was observed near the impinging region of the secondary flow on the wall. It was also found that a nearly isotropic and homogeneous turbulence field was caused by the promoter.