Drop-size distributions of sprays produced by fan-jet pressure nozzles

The drop size distribution of Newtonian and non-Newtonian liquid sprays was measured. The sprays were produced by fan jet pressure nozzles, used with paint atomizing equipment, operating in the pressure range of 500 to nearly 3000 psig. A collection device was contructed and droplets were captured on soot coated microscope slides. Subsequent sizing of the impacted particles, measured with a microscope, yielded drop size distribution data of accumulated volume per cent versus diameter. It was postulated that the initial cause of liquid breakup into a spray is due to wall shear existing at the exit plane of the nozzle. An experimental analysis was performed to relate the nozzle wall shear to the volume median diameter of the spray distribution. A linear correlation was found to exist on a semilog graph. Drop size distribution data on preorifice-nozzle combinations were also recorded.