TURBULENT-FLOW INDUCED BY AN IMPELLER IN A CLOSED TOROIDAL LOOP

Swirl flow induced by an impeller was studied in a toroidal geometry. Both mean and root mean square axial velocities were measured using an electrochemical velocity probe. The effects on the flow of the rotati onal speed of the impeller and the circumferential position inside the torus reactor were investigated. The values of the mean axial velocit y were compared with measurements obtained from residence time distrib ution method and from visualization experiments. The second part of th is paper is devoted to the study of turbulent toroidal flow by determi ning power spectrum density of axial velocity fluctuations. The turbul ent intensity in the torus reactor was shown to be homogeneous far dow nstream of the impeller; the turbulent intensity is strongly dependent on the radial coordinate near the agitator. The dissipation rate of e nergy, determined from the spectral analysis, is quasi-proportional to the Reynolds number. The dissipation rate of energy enabled the estim ation of Kolmogorov's microscales in the different studied axial and r adial locations. The results are consistent with the available literat ure.