Particulate Velocity Measurements in the Intra-Blade Passages of a Centrifugal Slurry Pump

The purpose of a slurry pump is to transport solids in a mixture called a slurry. It is a critical component of the slurry transport system in many industrial and mining related processes. In this investigation, Particle Image Velocimetry (PIV) was successfully utilized for measuring the particle velocities in the impeller intra-blade passages of an optically clear centrifugal pump (a transparent casing and a transparent three-blade impeller). An optically clear slurry consisting of sodium-iodide solution and 500 μm spherical glass particles was used. The experiments were conducted at speeds of 725 and 1000 rpm with volumetric concentrations of 2.5% and 5% respectively. In the impeller passage region, the highest particle velocities are generated on the suction side of the blade and in the blade trailing edge region as the blade sweeps through. However, these particle velocities are slower than the circumferential velocity of the blade tip. The particle fluctuation kinetic energy increased approximately 200% to 500% as the pump speed was increased from 725 rpm to 1000 rpm. The maximum fluctuation kinetic energy occurred on the suction side of the blade. The directional impingement mechanism is more significant at the pressure side of the blade. This mechanism becomes more pronounced as the speed increases. The random impingement mechanism caused by the fluctuation kinetic energy of the solids can play an important role on the blade surface (pressure and suction sides) and the casing wall erosion. Frictional wear mechanisms can be caused by the particles that do not stay suspended in the flow and accumulate into sliding beds along the pressure side of the blade. PIV measurements in the slurry pump model can add significantly to the understanding of the flow through the pump.