Atomization technology is widely used in the energy and chemical industries. Accurate and effective measurement and characterization of atomized particle size and size distribution is the premise of the research on atomization mechanism and performance optimization of atomizer. At present

the frequently used techniques for measurement of atomized droplet size

for example the laser particle size analyzer and phase Doppler analyzer based on light scattering or diffraction principle

can accurately measure spray of which particle size distribution is narrow and maximum particle size is under 2000 μm. But for the measurement of a large spray whose particle size distribution is wide or which contains large droplets

it is always difficult or even impossible to obtain an accurate result. This paper used the imaging method for measurement of such large spray

developed the image measurement system

wrote the image processing program

calibrated the measurement system

and used it for the droplet size distribution measurement and investigation of a nozzle spray. The research results showed that the imaging method could be effectively used for the measurement of droplet size and distribution of a large spray.