Rheological and Pipeline Flow Behavior of Corn Starch Dispersions

Abstract

The rheological and pipeline flow behavior of corn starch dispersions has been studied. It was found that the flow characteristics of these systems gave dilatant (shear thickening) behavior until a critical shear rate was attained at which point Newtonian behavior commenced. This critical shear rate, as well as the behavior of power law index and consistency index were found to be functions of percent volume concentration. Additionally, the behavior of these rheological parameters was explained on the basis of an existing theory describing shear thickening. Pipeline flow data confirmed that dilatant (shear thickening) fluids followed the Metzner-Reed friction factor relationships in the laminar region. The range of behavior was extended to fluids having n values of 2.92 and volume concentrations of 40.0 percent. Finally, it was found that transition and turbulent flow could not be attained for dilatant (shear thickening) corn starch suspensions. This principally occurred because the critical shear rates yielding Newtonian behavior were excluded.