INFLUENCE OF DESIGN ON MIXING EFFICIENCY IN A VARIABLE INTERMESHING CLEARANCE MIXER

The Variable Intermeshing Clearance (VIC) mixer possesses the unique f eature of the ability to change the inter-rotor clearance during the c ompounding process. To improve the mixing performance of the VIC mixer new designs are proposed. A fluid dynamics analysis package-FIDAP, us ing the finite element method was employed to simulate the flow behavi or in the VIC mixer. The problem of time dependent flow boundaries was solved by selecting a number of sequential geometries with 20 degree increments to represent a complete mixing cycle. Dispersive mixing was evaluated in terms of both the shear stress distribution and the elon gational flow components generated in the flow field. Distributive mix ing was studied numerically by means of tracking the evolution of part icles originally gathered as clusters. Our studies indicate that the n ew design of an enlarged chamber gives overall better dispersive and d istributive mixing performance than the traditional VIC. The VIC mixer with both an enlarged chamber and wider rotor blades design shows poo rer dispersive mixing but better distributive mixing capability. The e ffect of inter-rotor clearance on mixing efficiency is also discussed.