Image processing techniques for velocity, interface complexity, and droplet production measurement in the near-nozzle region of a diesel spray

An ultrafast shadow imaging arrangement using a double-pulsed femtosecond laser system in concert with a frame transfer CCD was used to record time-correlated image-pairs in the near-nozzle region of a dissymmetric diesel jet issuing from a single-hole injector. A region-matching procedure was applied to produce velocity maps of the spray. The time-correlated image data were binarized and segmented to produce comparative data sets which isolate the jet core and the surrounding droplet cloud. The velocity mapping process was applied to these segmented data sets, a variable characterizing the degree of atomization of the jet was defined by means of statistical analysis, and the curvature scale space of the jet core edge was used to extract a measure of its complexity.