Project summary: Flow from duct arrays
Accurate sorting of particulates is a problem fundamental to the food industry, the processing of rice grains being a typical example. Providing the sorting is of high quality, sorted products command a considerably higher price than unsorted ones.

The basic scientific methodologies for sorting are, first optical imaging, then pattern recognition and finally mechanical action. Paul Westwood’s research at University College, London in collaboration with Sortex Ltd has shown how new mathematics can help with the third of these methodologies in cases when air jets are used to remove unwanted particles.

Meticulously careful mathematical modelling is needed to understand how to design the nozzles for the very fine air jets that need to fire air at 20 metres per second in bursts at 300 cycles per second if they are to remove unwanted particulate economically.

The key issue is the interference between adjacent nozzles and consequent lack of sharpness of the jet boundaries. The precise mathematical quantification of this interference puts a well-defined upper limit on the accuracy that could ever be achieved for any given nozzle geometry, and this limit is an invaluable piece of information when new nozzles are being designed.

According to Sortex Head of R&D Mark Honeywood, Such mathematical research has a number of benefits: we understand the fundamental physics of the sorting process; we understand the design trade-offs; we improve our next generation developments and we tend not to over design…we add design cost where we know we will gain performance benefits.

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