Comparison of droplet distributions from fluidic and impact sprinklers

Junping Liu,Shouqi Yuan,Xingfa Liu,Xingye Zhu

doi:10.15302/j-fase-2015049

Abstract

To adapt to the trend toward low-energy precision irrigation, the droplet distributions for two new prototype sprinklers, outside signal sprinkler (OS) and fluidic sprinkler (FS), were compared with impact sprinkler (IS). A laser precipitation monitor was used to measure the droplet distributions. Droplet size and velocity distributions were tested under four operating pressures for nozzles 1.5 m above the ground. For the operating pressures tested, the mean OS, FS and IS droplet diameters ranged from 0 to 3.4, 0 to 3.5, 0 to 4.0 mm, respectively. The mean OS and FS droplet velocities ranged from 0 to 6.3 m$s, whereas IS ranged from 0 to 6.3 m$s. Being gas-liquid fluidic sprinklers, droplet distributions of the OS and FS were similar, although not identical. IS mostly produced a 0.5 mm larger droplet diameter and a 0.5 m$s greater velocity than OS and FS. A new empirical equation is proposed for determination of droplet size for OS and FS, which is sufficiently accurate and simple to use. Basic statistics for droplet size and velocity were performed on data obtained by the photographic methods. The mean droplet diameter (arithmetic, volumetric and median) decreased and the mean velocity increased in operating pressure for the three types of sprinkler.

Highlights

Sprinkler irrigation can be defined as any irrigation system which distributes water as discrete droplets through the air
Regarding the results of this study it should be noted that operating conditions were controlled but differed slightly between each measurement and the number of droplets measured on each occasion was different
Both authors reported a large variability in droplet diameters, with trajectories similar to those reported in this article

Summary

Introduction

Sprinkler irrigation can be defined as any irrigation system which distributes water as discrete droplets through the air. Sprinkler irrigation systems operated at lower pressure have received attention in recent years because the energy loss increases. Dwomoh et al have experimentally determined the droplet size distribution characteristics of one new type of sprinkler, complete fluidic sprinkler[25]. Zhu et al compared the mean droplet diameter of different types of fluidic sprinkler[26]. Information comparing droplet size and velocity distributions is still limited, and there have been only a few published reports. Namely outside signal sprinkler (OS), fluidic sprinkler (FS) and impact sprinkler (IS), were compared in this study at different operating pressures. The aims of this study were to: (1) compare the three sprinkler types for droplet size and velocity distributions, and (2) develop a simple mathematical model to represent droplet distributions for OS and FS

Objectives

Methods

Results

Conclusion