Application of Laser Interferometry to the Study of Droplet' Gas Phase Interaction and Behavior in Liquid Spray Combustion Systems

Abstract

The application or optical scattering techniques is described for the measurement of droplet properties in liquid sprays. Of the various approaches, phase Doppler interferometry demonstrates the highest promise for obtaining the information necessary to understand the formation and emission of toxic combustion byproducts in liquid-fueled spray reactions. The technique deduces drop size from the spatial variation in the imaged fringe patlern due to drop radius of curvature. Combined with the measurement of velocity via laser anemometry, the capability of sizing allows for the determination of continuous phase velocities as well as droplet size and velocity correlations. Such a capability is necessary to develop an understanding of the physical processes occurring within liquid combustion systems associated with incineration. Three applications are presented which are relevant to the formation of combustion byproducts: the effect of swirl on the dispersion of droplets, an assessment of spray symmetry, and measurements in a reacting environment. In addition, limitations of the phase Doppler technique relative to liquid combustion systems are outlined.