A SIMPLE PHOTOGRAPHING METHOD FOR PARTICLE MEASUREMENTS OF SPRAYS

This paper describes a simple and an inexpensive photographing method for determining size distributions, velocities and directions of flight of drops of liquid sprays. A simple optical arrangement has been developed in-which a magnification order ranging from 1.0 to 8.0 with a small depth of field of the photographed object was reached. With magnification order of eightfolds, photographs were taken of a small known volume of spray, and the images of the drops were counted and measured to give the size distribution. Velocities of the moving drops of the spray were also determined by taking two exposures on the same film and measuring the displacement of the drops in the interval time between exposures. The same photographing records were used to measure angles of drop flight directions. With magnification order of onefold on the negative film, the method was also used to observe the appearance of the spray. Since the method gives an increase in magnification at the imaging stage with small depth of field, it is applicable to take measurements of drops of dense liquid sprays.