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A novel technique based on optical patternation is described for three-dimensional diagnostic studies of aerosols used in analytical spectroscopies. The aerosol is illuminated with a thin laser light sheet to capture images of the fluorescence and Lorenz-Mie light-scattering signals from the aerosol field with a charge-coupled detector. These measurements allow for the rapid and nonintrusive elucidation of two-dimensional spray structures, planar mass distributions, and spatial droplet size distributions. The ratio of the fluorescence image to the Lorenz-Mie image is then utilized to construct a spatially resolved map of the volume-to-surface area mean of the aerosol (Sauter mean diameter). Three-dimensional maps of spray structure, mass distribution, and droplet size distribution are obtained for the entire aerosol field by image stacking. The technique is applied to the measurement of the droplet size over the aerosol field at distances of 5-30 mm from the nebulizer tip where droplet sizes ranged from 6 to 12 microm for a direct injection high efficiency nebulizer used in inductively coupled plasma spectrometries.

Volumetric 3-component velocimetry measurements have been taken of the flow field near a Rushton turbine in a stirred tank reactor. This highly unsteady, three-dimensional flowfield is characterized by a strong radial jet, large tank-scale ring vortices, and small-scale blade tip vortices. Approximately 15,000 3d vectors were obtained in a cubic volume; these data offer the most comprehensive view to date of this flow field, especially since they are acquired at three Reynolds numbers (15,000, 107,000, and 137,000). The fluid dynamics video shows various animations and combinations of the velocity and vorticity data. The volumetric nature of the data enable tip vortex identification, vortex trajectory analysis, and calculation of vortex strength. In the video, three identification methods for the vortices are compared based on: the calculation of circumferential vorticity; the calculation of local pressure minima via an eigenvalue approach ('λ 2 ') ; and the calculation of swirling strength again via an eigenvalue approach ('λ ci '). A 'swirl strength' criterion overall provides clearest identification of the tip vortices. The visualization of tip vortices up to 140 degrees past blade passage in the highest Reynolds number case is notable and has not previously been shown.The associated video can be viewed in mpeg-2 format and mpeg-1 format. The related article currently appears in the online first section

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