Spray formation of a hydraulic flat fan nozzle with an internally disturbed flow

Abstract

The study investigated the effect of internal disturbances to the fluid flow in a typical agricultural flat fan nozzle on the liquid sheet structure, wavelength, breakup position, and finally the droplet size distribution. The internal disturbances were generated by a cylindrical insert upstream of the final orifice, and the magnitude was determined by the insert diameter. The liquid sheet structures were recorded using short-duration photography. The quantitative effects of the insert size on the breakup length and volume median droplet diameter (VMD) were measured using a phase Doppler analyzer (PDA). The results showed that it is possible to increase the droplet size, such that the proportion of spray volume in small droplets less than 100 μm is reduced by 45%, without significantly affecting the other spray characteristics such as the spray angle and spray pattern at a normal working pressure for agricultural spraying.