Abstract
In this paper, characteristics of fluid flow and heat transfer of a drag-reducing dilute cationic surfactant solution in a channel and a tube are investigated to realize a highly efficient thermal transportation system. The addition of small amount of surfactant to water can reduce turbulent factional drag considerably, but many investigations, which are of full drag-reducing flow without disturbance, have showed that the heat transfer is reduced simultaneously. In order to recover the reduced heat transfer, the effect of some turbulent promoters and a row of delta winglets that generates the longitudinal vortices were tested in a two-dimensional channel. Further, the examination on the relation on the relation between heat transport and momentum one was carried out; it was found that the critical velocity corresponding to the critical Reynolds number at which the drag-reduction effect reaches a maximum value only depends on the concentration of the surfactant solution.
