Positron emission particle tracking in a mechanically agitated solid-liquid suspension of coarse particles

The technique of positron emission particle tracking (PEPT) is a unique non-intrusive Lagrangian flow visualisation technique which allows probing of opaque fluids and within opaque apparatus. It uses a single positron-emitting particle as flow tracer which is tracked in 3D space and time to reveal its full Lagrangian trajectory. PEPT was used to study the mixing of a concentrated suspension of coarse glass particles, containing up to 10.6 wt% solids, in a vessel agitated by a pitched blade turbine operating in both up-pumping and down-pumping modes. The Lagrangian information obtained was used to obtain a detailed Eulerian description of the two-phase flow inside the vessel. For the first time, it has been possible to determine the full 3D velocity and concentration fields of both the liquid and the solid phase within an opaque flow of this type.