Turbulent Flow Induced by an Impeller in a Closed Toroidal Loop

Abstract

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 rotational speed of the impeller and the circumferential position inside the torus reactor were investigated. The values of the mean axial velocity were compared with measurements obtained from residence time distribution method and from visualization experiments. The second part of this paper is devoted to the study of turbulent toroidal flow by determining power spectrum density of axial velocity fluctuations. The turbulent intensity in the torus reactor was shown to be homogeneous far downstream of the impeller; the turbulent intensity is strongly dependent on the radial coordinate near the agitator. The dissipation rate of energy, determined from the spectral analysis, is quasi-proportional to the Reynolds number. The dissipation rate of energy enabled the estimation of Kolmogorov’s microscales in the different studied axial and radial locations. The results are consistent with the available literature.