Abstract:A two-dimensional video disdrometer (2DVD) was used to measure drop size, drop velocity and drop angle from Nelson D3000 spray-plate sprinklers with a 4.78mm nozzle and operating pressure of 50, 100,150, 200kPa. The relationship among drop sizes, drop velocity and drop angle were analyzed. Results indicated that the relationship between drop diameter and distances along the sprinkler met exponential function. The volumetric mean diameter increased with the distance along the sprinkler increased, and at the same location from the sprinkler the average droplet diameter decreased with the increase of working pressure. The relationship between drop velocity and drop diameter met logarithmic function. Drop velocity increased with the drop diameter increased, and the effect of operating pressure on the relationship between drop diameter and velocity was not obvious. Drop angle decreased with the increase of drop diameter. When drop diameter was smaller than 1.0mm and operating pressure was at 50, 100, 150, 200kPa, 90.46%, 84.46%, 89.91% and 89.15% of the droplets descended perpendicularly to the ground, respectively. The rest of the droplets descended to the ground with angle between 30°~89°. When drop diameter was between 1.0mm and 2.25mm, the drop angle decreased rapidly with the drop diameter increased. And when drop diameter was greater than 2.25mm, the decrease trend became slower. The relationship between drop angle and drop diameter met a good linear function, and the effect of operating pressure on the relationship between drop angle and diameter was not obvious.