QUANTIFICATION OF FLOWING BED POROSITY NEAR THE OUTLET OF AN AXIALLY-SYMMETRICAL HOPPER USING SINGLE PROFILE PHOTON-ABSORPTIOMETRY

A new approach to densitometric quantification is described which uses a single photon transmission profile to provide tomographic data in axially symmetric objects. Using phantom tests, the specially developed computer algorithm is shown to perform data transformation with a high degree of accuracy. The main advantage of the novel application compared to the complete tomographic scanning is in its speed. The single profile absorptiometry technique allows the quantification of voidage variations in particulate flows over time resolutions of the order of a few seconds, thus making it especially suitable for investigation of flowing bed porosity in the immediate vicinity of a hopper outlet where the particles are known to accelerate significantly accompanied by significant dilation of the bed voidage. Application to powder flows in hoppers is discussed and a comparison is drawn with complete tomographic scanning.