Performance comparison of two interferometric droplet sizing techniques

In this paper, two interferometric techniques (Visibility/Itensity Validation and Phase Doppler) are critically examined in characterizing the spray of an air-assist nozzle with Sauter mean diameter of less than 35 microns. The two techniques are compared to each other and are evaluated against a Malvern diffraction unit. With the use of a rotating grating for Visibility/Intensity Validation, the interference techniques compare well to each other and to the diffraction method. The Phase Doppler technique is more easily applied to the spray, due largely to its broadened size and velocity ranges. The consistency of the interferometric results raises questions with regard to the use of the Malvern's most frequently applied distribution model.