Photographic Analysis of Sprays

This paper describes an experimental method for determining the size distribution and velocities of drops in a spray. Photographs are taken of a small known volume of the spray, and the images of the drops are counted and measured to give the size distribution. Velocities are determined by taking two exposures on the same film and measuring the displacement of the drops in the interval between exposures. Since a photographic method does not require any objects in the spray, the results are free of bias from disturbances of the flow pattern. The technique is applicable to sprays in which the diameters of drops range from 15 to 500 microns and gives results which differ by less than 20 per cent from the metered values of total flow rate.