FLOW VISUALISATION AND INSTANTANEOUS VELOCITY MEASUREMENTS OF SPRAY DRYER GAS AND SPRAY FLOWS USING PARTICLE IMAGE VELOCIMETRY

The technique of particle image velocimetry has been used to produce good quality instantaneous velocity maps of the gas and spray phases within a pilot plant co-current spray dryer. Good quality flow visualisation data provided by the use of the laser sheet as an intense source of illumination has indicated that the air and spray flows were characterised by an offset central jet with down flowing (right hand side) and up flowing (left hand side) wall streams. This is significantly different from what would normally be expected and it was suggested that this was possibly due to a maldistribution of the air phase on inlet to the dryer.