Model establishment of spraying width of thin-walled micro-sprinkling hose

Abstract: China is a big agricultural country, and agriculture is related to the stability and development of a country. With the continuous development of water-saving irrigation technology, micro-sprinkling hose as a new type of water-saving irrigation equipment has been widely promoted and applied in China in recent years. In order to facilitate the production upgrade and guide the planning and design of micro-sprinkling hose in agricultural irrigation, the experiment of spray width of thin-walled micro-sprinkling hose was carried out at Tianjin Agricultural Water Saving Technology Engineering Center (39°N, 116°E). Through consulting literature and market research, six kinds of micro-sprinkling hose commonly found in the market were selected, and their folding width, nozzle diameter, and nozzle elevation angle were measured and calculated. The spray width test of the thin-wall micro-sprinkling hose was carried out. The length of the sample to be tested in the test was 5 m, and the working pressure was divided into 4 grades from 0.03 to 0.06 MPa. The micro-sprinkling hose was laid up front to ensure uniform spraying on both sides of the micro-sprinkling hose. The water collecting bucket was arranged on one side of the micro-sprinkling hose, and five rays were arranged in the direction of the vertical micro-sprinkling hose. The ray spacing was 50 cm, and the spacing of the collecting bucket on the ray was 50 cm. At the end of the experiment, the amount of water in the bucket was measured and the spraying width was determined. At the same time, spraying droplet diameter test was carried out. Firstly, the quality of filter paper was measured by a precision balance. Then, the water droplets were connected with the filter paper at the head, middle and end of the spray stream along the micro-sprinkling hose. Then, the quality of the filter paper was measured again quickly by the precision balance. Finally, the number of water marks on the filter paper was counted. The diameter of water droplets was calculated by using the mass difference and the number of water droplets. The average diameter of water droplets in different parts was taken as the diameter of water droplets in micro-sprinkling hose. Considering factors such as air resistance, gravity and buoyancy acting on sprinkle water droplet, a mathematic model of sprinkle water droplet motion of thin-walled micro-sprinkling hose was build based on Newton fluid mechanics theory. Then theoretical formula of spray width was derived. The parameters of spray width formula were determined and the formula was validated on the basis of experimental data. At the same time, the influencing factors of the theoretical calculation formula were analyzed. The results showed that the theoretical formula of spray width of micro-sprinkler hose agreed with analysis values and experiment results well, the computational relative error of the six model micro-sprinkling hose comparing to experimental data was less than 10%. According to the experimental data analysis and theoretical formula deduction, the spray width of micro-sprinkling hose increased first and then decreased with the elevation angle of the nozzle, and the spray width reached the maximum when the nozzle elevation angle was about 40 degree. Spraying width increased with the increase of working pressure and within a certain working pressure range. Spraying width showed the same relationship with nozzle diameter within a certain orifice diameter range. The results showed that the theoretical formula had higher accuracy and could be widely used in the calculation of spray width, which provided a theoretical basis for the planning and design of micro-sprinkling hose irrigation system.