Eddy diffusivity of heat transfer in the radial direction for turbulent flow of mercury in annuli

Abstract

A basic experimental study of the fluid dynamics and heat-transfer characteristics of mercury, in fully developed turbulent flow through annuli, was carried out. This paper, the third in a series on this project, presents the results on the eddy diffusivity of heat transfer. Velocity and temperature profiles were measured in vertical annuli with heat transfer from the inner wall only, and experiments were conducted where the mercury either did not wet at all, or did thoroughly wet, the channel walls. The shapes of the ε H profiles were found to be similar to those of the ε M profiles, with the maxima and minima often occurring at or near the same radial locations, for the same experimental conditions. All minima occurred at the radius of maximum velocity, but the valleys in ε H profiles were relatively more shallow than those in the ε M profiles. The effect of wetting on the relative shape of the ε H profile, as in the case of the ε m profile, was found to be appreciable. When both walls were unwetted, the hydrodynamic behavior of the mercury was found [1] to be very similar to that of ordinary fluids. Although the present results obtained with unwetted walls do not agree with predictions based on existing theory, they do lend appreciable support to the method of Ramm and Johannsen [7].