Energy dissipation distribution and mixing in a torus reactor

Previous works devoted to the development of the swirl flow generated by ro tation of the marine screw impeller in the loop toroidal reactor show that the flow structure is characterized by the existence of a secondary flow. T he deformation of the axial velocity profile, due to the bends curvature an d the rotation of the agitator, modify considerably the friction and the tr ansfer near the wall. The objective of this work is to study the toroidal f low and to characterize the wall turbulence. The wall shear stress distribu tion in the torus were performed by using an electrochemical method. The me asurements of the wall shear stress were carried out in the inner and outer walls. The evolution of the wall velocity gradient with the longitudinal d istance depends on the location in the torus. These results allow to obtain information about the friction factor, which is compared with the one meas ured directly by using piezometric connections. The experimental determinat ion of the axial dispersion coefficient is obtained by using the dispersion plug flow model with a total recirculation. Finally, a relationship betwee n the turbulent characteristics and the mixing parameters has been establis hed.