Experimental validation of numerical simulations of the kneading disc section in a twin screw extruder

A comparison of the results of a 3D model for the simulation of flaw in the kneading disc region of a fully intermeshing twin screw extruder has been done against particle image velocimetry (PIV) experimental data. Experiment al results using a geometry with an extended first and last kneading disc t o capture the simplified inlet and outlet boundary conditions, are in good qualitative agreement for low flow rates. The results showed good agreement at flow rates less than 5 mL/s and rotation speeds of 60 rpm, while above that there was poor agreement. These results highlight the importance of th e use of appropriate boundary conditions for the accurate prediction of the flow field. The flow field within the kneading discs with forward conveyin g elements placed before and after the kneading discs was also measured. Fo r a flow rate of 8.5 mL/s and 60 rpm, results showed good agreement when co nveying elements were deployed before and after the kneading blocks whereas for lower flow rates there was poor agreement.