AbstractsEngineering

The Sonolator liquid whistle is an industrial inline mixer used to create complex multiphase mixtures which form components of high value added liquid products. Despite its wide use, this device’s mechanism of operation is not well understood which has led to this combined experimental and computational study to elucidate key phenomena governing drop and jet break-up. The work has focused on single phase Particle Image Velocimetry (PIV) measurements of a model device to validate single phase Computational Fluid Dynamics (CFD) simulations to gain basic understanding of the flow fields which are responsible for the breakage behaviour, assuming dilute dispersions. Multiphase pilot plant experiments on a silicone oil-water-SLES emulsion have been used to characterise the droplet size reduction in a pilot scale Sonolator for both dilute and medium concentrations of the dispersed phase. An empirical model of droplet size was constructed based on pressure drop, dispersed phase viscosity and surfactant concentration. This empirical model was compared with the droplet breakage theories of Hinze, Walstra and Davies. Extra work mentioned in the appendices includes studies on cavitation in the Sonolator, with the cavitating flow conditions identified and the contribution to emulsification considered, and the usage of population balance methods to simulate droplet breakup in the environment indicated by CFD/PIV studies in order to investigate how the droplet size distributions measured in pilot plant studies came about.