Free-surface shape in unbaffled stirred vessels: Experimental study via digital image analysis

For each investigated geometry, the deformed free-surface was analyzed at different impeller speeds. Different geometries of the vessel were analyzed, by varying impeller distance from vessel bottom as well as agitator type (Rushton turbine, Lightnin A310, Pitched Blade Turbine). It is shown that impeller design strongly affects the free surface profile, and in turn the impeller speed at which the free surface reaches the impeller. A model was developed to fully describe free-surface profile at all agitation speeds and for all investigated geometries, suitable for being adapted to experiments by means of physically consistent parameters adjustment.