Hydraulic performance in low-pressure sprinkler based on droplet spectrum characteristics

Low-pressure sprinklers are essential components of large-scale mobile sprinkler irrigation systems. However, comprehensive quantitative research on their water spray performance remains limited, and systematic comparisons of raindrop spectrum characteristics, kinetic energy distribution, and their effects on soil infiltration across different sprinkler types (fixed disc, rotating disc, oscillating disc) have been insufficient. This study utilised high-precision 2D-Video-Distrometer technology to systematically quantify the differences in water spray performance among three types of sprinklers: fixed disc (D3000), rotating disc (R3000/S3000), and oscillating disc (O3000). The results demonstrated that the rotating sprinkler significantly increased unit volume kinetic energy ( KE v ) through centrifugal fragmentation, with KE v exhibiting exponential growth along the spray range. The oscillating sprinkler achieved the highest uniformity (≥95%) via three-dimensional jet flow but experienced a 15%-20% reduction in spray range. A kinetic energy model constructed using a natural exponential function (R 2 ≥ 0.92) demonstrated that large-diameter water droplets ( d > 4 mm) contributed 21.19%-24.69% to the total kinetic energy. The fixed sprinkler caused an 80.24% decrease in soil infiltration rate due to concentrated kinetic energy, whereas the oscillating sprinkler mitigated this effect by reducing kinetic energy impact, limiting the infiltration rate drop to within 10% and showcasing superior erosion resistance. This study provides a scientific foundation for the precise selection of low-pressure sprinklers and introduces a novel approach to sprinkler design optimisation through raindrop spectrum analysis. • Application of 2D-Video-Distrometer to assess sprinkler hydraulic performance. • High-speed rotation of the spray plate reduces the spraying range of the Sprinklers. • Kinetic energy per unit volume of droplets increases exponentially along the range. • Rotation of the spray plate adds to the kinetic energy per unit volume of droplets. • Exponential model simplifies kinetic energy prediction based on radial distance.