Evaluation of pulsed laser holograms of flashing sprays by digital image processing and holographic particle image velocimetry Original Research Article

The present paper deals with the analysis of the disintegration process of both subcooled and superheated sprays generated in a flat spray nozzle. Both the macroscopic structures of a spray, such as the breakup-length and the spray-angle, and its microscopic structures, such as the number, the size, the location, and the velocities of the generated droplets as a function of varying injection conditions have been investigated. The short time holography has been applied as the measuring technique. Two holograms of the generated spray are taken simultaneously which results in two three-dimensional (3-D) reconstructions of the spray, seen from different directions. Computer based algorithms have been developed to determine the quantities to be measured that are stored on the holograms. A stereo-matching module correlates both views and determines the position and/or the velocity of each droplet. The applicability of the employed holographic technique and of the filtering and correlating modules is proven by the presented results.