Spray and particulate diagnostics in combustion systems - A review of optical methods

The droplet size distribution plays a key role in the ignition and subsequent combustion of the fuel spray in gas turbines, Diesel engines, and other liquid fueled combustion devices. The increased need for nondisturbing real time in situ measurements of particle size has motivated the development of a wide variety of optical methods in recent years. The optical fundamentals relevant of optical particle sizing instruments are reviewed and a description is presented of a number of specific techniques which have been developed for size measurements. Attention is given to Mie scattering, nonspherical particle effects, imaging methods, classical optical particle counters, forward lobe ratio methods, diffraction methods, crossed beam fringe methods, droplet sizing by means of fluorescence, and extinction methods.