Quantitative analysis of liquid jets breakup with SAXS

Full text: The breakup of liquid jets represents a wide area of research in the field of multiphase flows, fully justified by their wide presence both in industrial and in scientific applications. Moreover, the recent development of microfluidic systems has raised great interest in understanding the flows in small spatial dimensions. Such interest has been further increased due to the evolution of free electron lasers and the consequent need to develop new, high throughput techniques to characterize biological macromolecules. Jet instability has been widely described both theoretically and by performing simulations, however there is still need to have accurate sets of experimental data. In fact most of them are based on light scattering which is disturbed by reflection, absorption and multiple scattering of droplets and air interface morphology, and on camera imaging which is limited by the dimension of the phenomena that can be seen. In the present communication we want to show the potentiality of synchrotron SAXS in providing quantitative information on the dynamics of liquid jets at the nanoscale. To this purpose, we have investigated free liquid jets in air with circular nozzle geometry of different diameters (450μm-100μm), flow rates (2-10 ml/min), and solvents (water, ethanol, isopropanol and their mixtures). We determined their time dependent morphology and their breakup length in the Rayleigh and rst wind-induced regimes. The resulting data are considered as basis for the use of free jet micromixers to examine the evolution of chemical and biological reactions by SAXS. (author)