Experimental Study Of Droplets Deposition Distribution Based On Digital Images

The pesticide droplets deposition distribution on the field and crops directly affects the effect of weeding and deinsectization.The research purpose of this thesis is to study the droplets deposition distribution based on digital image technology,obtain the distribution law of droplets in greenhouse.It laid the foundation for improving the utilization efficiency of pesticide,decreasing the environmental pollution and the innovation of the pesticide application technology.The glass slide which is coated by white paint was used as sampling card to sample the droplets deposited.A hardware system was designed to obtain the droplets images,and a software was coding by Visual C++6.0 combined with Object-Oriented modularization programming method to process the droplets image.This software can realize the Image Pre-processing,system calibration,obtaining the droplets characteristic parameters which included droplets equivalent diameter,spraying coverage and droplets density.The experimental data was processed by 3-D visualization tool—3D Surfer using Radial Basis Function.The droplets spatial distribution and contour maps in the 56m greenhouse with single spraying,72m greenhouse with twice spraying and on the greenhouse cross section were drawn.And at the last the influence of fan speed on droplets distribution was studied.Through the massive experiments and works,the main conclusions are as follows:(1) In the 56m greenhouse with single spraying,the droplets equivalent diameter and spraying coverage was bigger in both sides than central axis of the greenhouse, while droplets density is opposite.The peak values of droplets equivalent diameter and spraying coverage respectively appeared in both sides of the greenhouse which was 25m away from entrance,there were three peak values of droplets density in central axis of the greenhouse which were 13m,35m and 52m away from entrance.(2) In the 73m greenhouse with twice spraying,the droplets equivalent diameter and spraying coverage was reached the max value in the 17m and 53m of greenhouse, and decreased gradually forward and backward.The droplets density reached the min value in the 20m and 53m of greenhouse.The results also demonstrated that the fluctuation of droplets characteristic parameters were smaller with twice spraying than single spraying.(3) In the 42m cross section of 56m greenhouse,the droplets distribution showed the trend that in the margin of the greenhouse was bigger than in the central area.(4) The influence fan speed on droplets distribution:the droplets equivalent diameter was no significant change in the first and last 15m areas of the greenhouse with the rise of fan speed,in the 10～40m middle area of greenhouse the equivalent diameter increased with the increasing of fan speed;the fan speed had no obvious effect on the spraying coverage in the first and last 10m areas of the greenhouse,in the 10～45m middle area of greenhouse the spraying increased with the increasing of fan speed,but the influence was not obvious in the range of 30～40Hz;in the 0～20m and 40～55m area of greenhouse,the droplets density was no significant change,and in the 20～40m area of greenhouse,the droplets density was gradually decreasing along with the increasing of fan speed.