Full field diffraction particle sizing

The study of combustion in direct injection Diesel engines demands detailed understanding of the behavior of the injection. Understanding the injection involves characterizing the distribution of fuel droplet sizes throughout the spray. This need to determine the droplet sizes in fuel sprays motivates the development of a diffraction based particle sizing technique. The diffraction particle sizing technique developed is especially good for analyzing transient, dense sprays such as Diesel injections.; Analyzing the far field diffraction pattern produced by images of particles retrieves the particle size distribution. The technique captures images of particles, interrogates the images to obtain far field diffraction patterns, and inverts the intensity distributions of the diffraction patterns to yield particle size distributions. Because it analyzes a plane of captured images of particles, the technique acquires spatial maps of particle size taken at an instant in time. Acquiring this spatially resolved size information over the full spray field is a unique ability of this diffraction sizing technique; in transient applications, spatially resolved information is more meaningful than the time-ranging data acquired by most sizing techniques. Because this diffraction-based diagnostic does not count or image individual particles, dense groups of particles do not seem to hinder its performance.; The diffraction based diagnostic was implemented in a series of applications. The initial implementations assayed the performance of the technique; later applications used the technique to learn about spray behavior. Analyzing apertures and droplets of known size validated the accuracy of the technique. Subsequent implementation to two Diesel sprays evaluated the efficacy of the technique in increasingly difficult experiments. Implementation of the technique to sprays from a series of injectors obtained useful information about the behavior of the Diesel sprays.; Analyzing these sprays yielded detailed and averaged size information. Particle size distributions presented the detailed size information characteristic to the technique. Maps of d{dollar}sb{lcub}32{rcub}{dollar} throughout the sprays displayed more general size trends in the injections. This spatially resolved data confirmed the reliability of the sizing technique, revealed the shot-to-shot variation of the injections, and identified trends in size dispersion related to the hole shapes of the injectors. Obtaining applicable information from practical sprays demonstrated the utility of this diffraction particle sizing technique as an experimental diagnostic.