Particle Velocities in the Rotating Impeller of a Slurry Pump

The velocities of the slurry particles in the impeller of a centrifugal slurry pump were obtained utilizing Particle image velocimetry (PIV) technique in conjunction with refractive index matching. Tests were performed in an optically clear centrifugal slurry pump at speeds of 725 rpm and 1000 rpm using a slurry made up of sodium iodide solution as a working fluid and glass beads (500μm mean diameter) as solid particles at volumetric concentrations of 1%, 2%, and 3%. In the intra blade region of the impeller, the highest particle velocities were obtained in the suction side of the blade and in the blade trailing edge region as the blade sweeps through and velocity magnitude increases with the increase in the pump speed. But this magnitude was less than that of circumferential velocity of the blade tip. The average particle velocities were obtained and it was found that the average particle velocity decreases with increase in concentration. The fluctuating component of particle velocity, which is related to the fluctuation kinetic energy were obtained. With the increase in the particle volumetric concentration, fluctuation kinetic energy decreases and the maximum fluctuation kinetic energy typically occurs on the suction side of the blade. The slurry particles are pushed on the pressure side of the blade and slide on it which can result in frictional wear. These results are discussed in this paper.