APPLICATION OF LASER DOPPLER ANEMOMETRY TO MEASURE VELOCITY DISTRIBUTION INSIDE THE SCREW CHANNEL OF A TWIN-SCREW EXTRUDER

摘要

Velocity measurements inside the screw channels of a co-rotating, self-wiping twin-screw extruder (ZSK-30) have been carried out using the noninvasive technique of Laser Doppler Anemometry. A two-dimensional Argon-ion laser Doppler system was used to measure tangential and axial velocity components in one of the screws, away from the intermeshing zone. Heavy com syrup with naturally occurring panicles was used in the extrusion experiments. The measured tangential velocity distribution agreed with the expected distribution for a Newtonian fluid. Measurements also indicated that near the screw root and away from the flights, shear rates were substantially lower as compared to the shear rates near the barrel. The results indicated that this technique is suitable for making velocity measurements in a twin-screw extruder using model fluids.