A New Theory Improves the Correlation of Blend Time Data from Turbulent Jet Mixed Vessels

A number of papers have been published over the last 50 years reporting the results of blend time measurements made in jet mixed vessels. These data have been correlated empirically relating a dimensionless blend time to various geometrical ratios associated with the vessel and jet nozzle. This paper presents a re-analysis of these data based on the argument that the local turbulent kinetic energy dissipation rate at the end of the jet path controls the mixing rate for the whole vessel. The new model correlates data taken in vessels of 0.61, 1.68, 3.98, measured by the Fluid Mixing Processes (FMP) consortium and 36m diameter, by Van de Vusse, with a relative standard deviation of ±11%. Also, the new model predicts the existence of an optimum vessel geometry for a jet mixed vessel to minimize the power input required to achieve a desired blend time which the previous correlations did not. Finally, examples of full scale jet mixer design are given.