An opposed jets device for studying the breakup of dispersed liquid drops

Many studies on the dispersion of one liquid in another concentrate on the deformation and breakup of a single drop in a well defined flow. This paper describes the design of a device, which has not yet been used in this field. The concept makes use of the stagnation flow of two opposed jets in a closed circuit. A numerical study results in channel geometries for plane hyperbolic flow, which is purely extensional, and for a flow type which combines extension and vorticity. A device with dimensions of several centimeters suffices to study deformation of a 1 mm drop. Experiments show that the model for plane hyperbolic flow is obeyed in a large region around the stagnation point. A control system is developed to position the deforming drop steadily at the, principally unstable, stagnation point. A control cycle consists of determination of the drop position and calculation and realization of the required flow adjustment. In the present experimental setup the deformation of a drop in 2-dimensional elongational flow can be studied via video recording. The setup chosen not only allows for model lqiuids but can be adjusted to allow for polymer melts as well.