Water droplet distribution for non-circular sprinkler nozzles

Abstract

<div><p>Objective: The study sought to investigate the distribution law of the diameter, velocity, and kinetic energy of water droplets in specially designed nozzles. Method: An indoor windless water droplet dispersion test on the PY15 rocker-arm sprinkler was performed using a video raindrop spectrometer at five working pressures: 100 kPa, 150 kPa, 200 kPa, 250 kPa, and 300 kPa. Result: The equal-flow nozzle has the following range: circle > rhombus > ellipse; the shape coefficient of the special-shaped nozzle decreases with increasing outlet diameter and increases with increasing aspect ratio; the diameter of the rhombus nozzle’s water droplet increases radially. Conclusion: Under the same working pressure, the diameter of the water droplet at the end decreases as the form coefficient increases. The wider the outlet’s diameter, the longer the range and the greater the increase in the velocity of the water droplets. The larger the aspect ratio, the shorter the range and the greater the average diameter and velocity of the droplets. The elliptical nozzle has the lowest droplet velocity increase as droplet diameter increases. The impacting kinetic energy and growth range of water droplets per unit volume at the same position decrease as the pressure increases. Along the radial direction, the droplet velocity and diameter are logarithmic, while the droplet kinetic energy and diameter are exponential and linear functions. The relationship between the shape coefficient, outlet diameter, aspect ratio, and droplet distribution characteristics of the shaped nozzle can be simulated using the fitting coefficients of the three droplet distribution prediction models, all of which are above 0.9.</p></div>