Influences of nozzle parameters and low-pressure on jet breakup and droplet characteristics

Experiments were carried out to investigate the influences of nozzle geometric parameters and injection pressure on jet breakup characteristics using a high-speed photography (HSP) technique. The flow rates and spraying ranges of sprinkler with different nozzles were measured. In this research, HSP technique was also used to photograph the drops emitted by sprinkler with different nozzles at different pressures, photographs were taken at different horizontal distances from the sprinkler and the equivalent circle diameter was used to represent the particle sizes. Based on HSP technology, the effects of flow velocity and nozzle geometric parameters on jet breakup length were studied, and the droplet diameters with different nozzle types were obtained. The result showed that for the sprinkler with different nozzles, the breakup length decreased with the increases of pressures. At the nearby (3-9 m) region and distant (12-18 m) region of sprinkler, the droplet diameters of sprinkler with type B nozzle were the largest, which meant the sprinkler with type B nozzle was the optimal choice by synthesizing the droplet diameter distribution. The fitting relationship of jet breakup length with Reynolds number and Weber number (Re and We), and the regression equation of the end droplet diameters were deduced with errors of less than 5% and 4% respectively.