Study of the influence of blade speed on the performance of a powder mixer using positron emission particle tracking

The technique of positron emission particle tracking permits the tracking of a single radioactive tracer particle moving at up to 2 m/s in a dense and optically opaque medium. It has been used to investigate the relationship between blade speed and particulate motion in a 5 litre ploughshare batch mixer. The radial and axial velocity fields were found to scale with the blade speed. Above a critical blade speed, the axial motion developed into two circulation cells, with particles exchanging periodically between the two. Varying the size of the tracer particle had a significant influence on the frequency of this exchange whilst leaving the bulk motion within each cell essentially unchanged