3-D numerical simulations of nonisothermal flow in co-rotating twin screw extruders

Three-dimensional nonisothermal flow simulations in the kneading disc regio ns of co-rotating twin screw extruders were performed using a finite elemen t method. The standard Galerkin method and penalty function scheme were app lied to the flow field. The streamline-upwind/Petrov-Galerkin scheme was us ed in the temperature field to reduce numerical oscillation. The simulation s were carried out under the operational conditions of The Japan Steel Work s TEX30 machine for various rotational speeds. The configuration was ten 2- lobe kneading discs with a 90 degrees stagger angle. Experimental observati ons were also performed to validate the numerical simulations under the sam e operational conditions. The pressure in front of the tip in the rotation direction was higher than behind the tip, and the region behind the tip som etimes had a negative value. Since variation of the pressure gradient in th e axial direction causes forward;ard and backward flows in the disc gap reg ions, the disc gap regions play an important role for mixing. The temperatu re becomes higher with increasing rotation speed due to high viscous dissip ation. A high temperature was observed on the disc surface, in the disc gap , and in the intermeshing regions. The numerical results of pressure profil es with the rotation and the temperature in the axial direction were in goo d agreement with the experimental observations.