A laboratory spiral disk extruder for flow visualization

A laboratory spiral-disk extruder for the study of gas entrainment phenomen a is presented. The rotating plate is transparent, thus allowing for the di rect observation of the steady liquid-gas interface when operating under st arve-fed conditions. The extruder flow is modeled with the conventional sin gle screw extruder approach. This leads to a simple working equation for th e spiral screw, which is formally identical to the classical screw equation for standard extruders. The model is validated by comparing the prediction s with experimental data taken in both closed and open die configurations.