Experimental investigation of fibre particles in a turbulent stirred tank with DPIV

Abstract

In this paper, the experiments of fibre particles in turbulent solid-liquid two-phase flow fields using Digital Particle Image Velocimetry (DPIV) were conducted in a baffled tank stirred by standard six-blade Rushton. Fibre particles with different aspect ratios of 18.8, 25.0 and 37.5 are experimented with impeller speed from 100 to 400rpm, respectively. Both the orientations and the velocities of the fibre particles in the stirred tank under different conditions are obtained, as well as the turbulent velocity field. It is found that velocity of solid phase is very close to that of liquid phase. In the range of investigated solid concentration, liquid velocity exhibits close agreement at different solid concentrations. The velocities of two-phase flow are slightly greater than those of single phase. The influences of impeller speed, aspect ratio and solid concentration of fibre particles on the velocity field are discussed. With the increase of impeller speed, radial and axial particle velocities increase accordingly. With the increase of impeller speed and aspect ratio, orientation decreases slightly. Orientation seldom has any change with the increase of solid concentration. Meantime, the velocity profiles of solid-liquid two-phase flow with spherical particles are also compared with those of fibre particles. There is little discrepancy between velocities of fibre particle and spherical particle. All these can be used as the basis for industrial design as well as further simulation.