Measurement of internal circulation in droplets using laser-induced fluorescence

A diagnostic technique based on the oxygen quenching of laser-induced fluorescence from naphthalene has been developed to investigate whether internal circulation is important in submillimeter hydrocarbon droplets. Images have been obtained in 300-500 microm diam droplets of decane. Oxygen is absorbed into the surface liquid of initially oxygen-free droplets and quenches the naphthalene fluorescence. The resulting fluorescence image, including darker zones where oxygen is present, is recorded on a 2-D CCD detector. Computer processing of the images obtained with and without oxygen present reveals internal circulation patterns.