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

The study investigated the effect of internal disturbances to the fluid flo w in a typical agricultural flat fan nozzle on the liquid sheet structure, wavelength, breakup position, and finally the droplet size distribution. Th e internal disturbances were generated by a cylindrical insert upstream of the final orifice, and the magnitude war, determined by the insert diameter . The liquid sheet structures were recorded using short-duration photograph y. The quantitative effects of the insert size on the breakup length and vo lume median droplet diameter (VMD) were measured using a phase Doppler anal yzer (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 mu m is reduced by 45%, without significantly affecting the other spray characteristics such as the spray angle and spray pattern at a normal work ing pressure for agricultural spraying.