Particle Image Velocimetry Measurements of Flow Inside a Hydrocyclone With an Air Core

Hydrocyclone separators are widely used in the oil and mining industries to sort, classify and separate solid particles or liquid droplets within liquid suspensions. In this study, the liquid-air flow inside a mining hydrocyclone is investigated using particle image velocimetry (PIV). Previous work completed by Ke (2016), using the same technique and experimental setup as the current study, mainly focused on the flow velocities in the radial-tangential plane within a hydrocyclone running with an air core. Due to optical limitations, the velocity measurements in the radial-tangential plane were limited to the inlet head. Previous work by Chinmay et al (FEDSM 2017) was also performed which concentrated mainly on the dimensions of the air core. The study revealed several physical phenomena and flow patterns of the multi-phase flow in a hydrocyclone. An air core is generated along the central axis of the hydrocyclone, as the underflow is open to atmosphere. In this study, the flow field in the radial-axial (r-z) plane has been investigated, and measurements have been obtained in the conical regions outside of the inlet head including the center (axially) of the cyclone. Particle Imaging Velocimetry (PIV) method was used with a laser as the light source in order to obtain experimental data for the purpose of developing and validating computational models of hydrocyclone flows. Refractive index matching technique was used, with the hydrocyclone model being made of clear acrylic material. The test liquid used in the experiments was sodium iodide aqueous solution (63.3% NaI by weight), in order to achieve a refractive index match between the curved inner cyclone walls and test fluid. The seed particles used in the experiments were 10 μm silver coated hollow glass spheres which were introduced into the flow by global seeding. Three fields of view (FOV) were investigated in the r-z plane of the hydrocyclone. Two dimensional velocity vector maps were obtained in each of the fields of view. Additionally, a SONARtrac unit was installed in the overflow piping in order to measure the % air content of the cyclone overflow. The PIV and % air content measurements will be presented and discussed.