Flow field analysis of a cavity transfer mixer

Abstract

The cavity transfer mixer (CTM) was primarily designed as a distributive mixing device to be used as an add-on unit to existing extruders. In determining the CTM overall mixing efficiency as well as its potential use for various applications, the flow patterns/characteristics within this mixer must be well understood. In this work, a fluid dynamics analysis package, FIDAP, based on the finite element method was employed to simulate the flow patterns in a CTM with 6 rows and 4 cavities per row. A 3D, isothermal flow analysis was carried out and the fluid of choice was a flexible polyvinylchloride whose rheological behavior is described by a power-law model fluid. The flow field was characterized in terms of velocity profiles, pressure distributions, shear rates/shear stresses generated and a parameter A quan-g the elongational flow components. The results of the flow simulations were compared with experimental data. The CTM potential use for dispersive mixing was discussed.

Troubleshooting and mitigating gels in polyethylene film products

“…The CTM 22,23 is constructed by positioning concave cavities on the screw shaft and into the barrel wall. Different cavity shapes are practiced commercially.…”

Refractive Index-Matched PIV Experiments and CFD Simulations of Mixing in a Complex Dynamic Geometry

“…The first three-dimensional simulation of a dynamic mixer was performed to characterize the flow fields based on the finite element method, and the potential use of the mixer for dispersive mixing was proposed by Wang and Manas-Zloczower. 8 Grosso et al 9 conducted comprehensive three-dimensional simulations to assess the mixing processes in a CTM. Their work found that the number of cavities per row and the dimensionless number k defined as the ratio between the axial and the tangential velocity of the fluid at the inlet are the two critical factors for the performance of the dynamic mixer.…”

Extrusion Technology for Manufacturing Polymer Blends

“…The CTM mixer [33,34] is a device that is attached to the end of an existing extruder. In general, these mixers provide improved mixing over traditional secondary mixers, but they are more complicated and costly to produce, require higher maintenance levels, and they tend to have higher levels of wear.…”

“…For example, the performance of several mixing elements were evaluated and compared at the Polymer Processing Institute by using the TSMEE (twin-screw mixing elements evaluator) [34].…”