Vortex Structures around a Flat Paddle Impeller in a Stirred Vessel

Abstract

An experimental study of the structure of the roll and trailing vortices formed around the blades of four flat paddle impeller in a stirred vessel has been carried out Angle resolved measurements of all three velocity components were performed by synchronizing laser Doppler velocimetry with a rotary encoder coupled to the impeller shaft. Almost all data were obtained in the θ=0°plane. located half-way between two baffles. This experimental method make it possible to capture the details of the vortical structure behind the impeller blade. The formation of roll and trailing vortex is more evident in the resultant axial and circumferential mean velocity vectors and contours of mean vorticity. The size, shape and location of trailing vortex are shown and compared with the results of Rushton turbines.