Influence of operating parameters on jet breakup characteristics of low-pressure rotary sprinklers

High-speed photography technology is adopted in this paper to systematically investigate the entire process of water jet breakup into droplets in the air after ejection from the water splitter tray of low-pressure rotary sprinklers under varying operating pressures and nozzle diameters. The experimental results revealed significant dependencies of jet breakup length, characteristic jet velocity, droplet characteristics, including their size and velocity, on the operating pressure and nozzle diameter. There are three types of spray water jet breakup, which are the split jet breakup, column jet breakup, and liquid-film jet breakup. A statistical linear regression model links the jet breakup length to the working pressure and nozzle diameter, and the breakup length of the water jet increases with decreasing working pressure or increasing nozzle diameter. Meanwhile, an increase in working pressure or nozzle diameter leads to a high flow rate, which in turn results in a power-law growth of the characteristic jet velocity. A quantitative nonlinear model of the breakup droplet velocity concerning its size and operating parameters is proposed through parametric analyses, and it is revealed that the breakup droplet velocity increases in a power-law manner with increasing pressure or nozzle diameter, and exhibits a logarithmic increase with increasing droplet size. This paper quantifies the relationships between jet breakup dynamics and operating parameters through experimental investigations and analytical modeling, which offers a valuable reference and experimental basis for performance-driven optimized design of industrial spray systems.