Structure of turbulent velocity field in the discharge stream from a standard Rushton turbine impeller

Abstract

The radial discharge jet from a standard Rushton turbine was investigated by the Laser Doppler Anemometry (LDA) method. Several distances from the impeller blades (in the radial direction) were chosen for the measurement of axial profiles: all three velocity components (radial, tangential and axial) were measured at each point of the axial profile. The obtained velocity time records were analysed and averaged results were decomposed into three parts: mean ensembleaverage, random and periodic. The ratio of the derived periodic part of the velocity was evaluated in each measurement point and for all velocity components. The obtained results indicate the regions where the periodic part of the velocity has significant effect and where the contribution of this part is almost negligible. Although the values of the periodic part of all velocity components have a rather similar range, the spatial distributions are different in the investigated region.

Keywords

• Rushton turbine
• LDA
• discharge stream
• agitated vessel