Collect. Czech. Chem. Commun. 1996, 61, 856-867

Experimental Study of Turbulent Macroinstabilities in an Agitated System with Axial High-Speed Impeller and with Radial Baffles

Oldřich Brůhaa, Ivan Fořtb, Pavel Smolkaa and Milan Jahodac

a Department of Physics, Czech Technical University, 166 07 Prague 6, Czech Republic
b Department of Chemical and Food Process Equipment Design, Czech Technical University, 166 07 Prague 6, Czech Republic
c Department of Chemical Engineering, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic


The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.

Keywords: Macroinstability; Axial impeller; Mixing in transient region.