Evaluating Fuel Injectors with High Speed Laser Imaging Techniques

A pulsing ultraviolet laser is used to illuminate fuel injector sprays. The spray images are formed on a vidicon and presented on a TV monitor at high magnification. The mechanics of fuel atomization such as droplet formation, ligaments, impingement and evaporation are described. Such things as start time and stop time of an injector are shown. Other characteristics such as bounce of the pintle, erroneous multiple injections, poor closing and leaking are covered. An in-depth study is given showing “time slices” taken through an injected spray. Pencil beam injections, wide angle sprays, hollow cones, nonsymmetrical and skewed sprays are shown on the TV screen for injectors operating in the Static and Dynamic Mode. The Image Analyzer used in this study provided particle size counts and provides data print out showing Percent by Count, Percent by Weight, Mass Median Diameter and Sauter Mean Diameter together with Size Distribution Plots of the sprays.