Bubble size distribution and energy dissipation in foam mixers

Abstract

The bubble size distribution of a foam produced in a rotor‐stator mixer has been determined as a function of several mixing parameters such as the rotor speed, residence time, gas/liquid ratio and the viscosity of the liquid used. A Newton‐Reynolds expression for a foam mixer has been determined using energy consumption measurements. Two types of shear fields have been distinguished in the foam mixer, laminar and turbulent, the type of shear field depending on the properties of the foam mixer. After a certain mixing time the bubble size distribution characterised by the mean bubble size was found to reach a stationary value. The stationary bubble size distribution has been correlated with the mixing conditions by a critical Weber number. Both in the laminar and in the turbulent shear field bubble size distributions have been determined as a function of several mixing parameters.