A SIMPLE PROCEDURE TO DETERMINE POWER-LAW CURVES - THE FLAG VISCOMETER

Average shear stress and average shear rate in a flag type mixer visco meter were approximated by mathematical equations using a concentric c ylinder analogy. Flow curves for selected power-law fluids (CMC soluti ons and salad dressing) were then obtained and results showed the adeq uacy of the developed procedure to characterize the rheological proper ties of power-law fluids. Procedure is simple, reduces significantly d ata collection and eliminates the need of sophisticated instrumentatio n. The influence of the impeller-to-cup diameter ratio, the impeller r otational speed and fluid properties on the values of the average shea r rate was evaluated using established mixer viscometry methods.