| Research on structure design and performance optimization of DWPT sprinkler is one of the contents of China National Key Research & Development Program“Research and Development of Green and Efficient Water-saving Irrigation Equipment Suitable for Northwest Typical Agricultural Areas in Northwest China”(Project No.2016YFC0400202).At present,China is short of water for agricultural production,so it is necessary to continuously optimize and improve the atomization technology of water-saving irrigation to obtain a higher standard,so as to achieve the goal of water-saving and energy saving.In order to solve the problems of small atomizing range and high working pressure of atomizing nozzle,a kind of DWPT dispersing atomizing nozzle with simple structure,reliable operation and low working pressure was designed.This paper introduces the working principle and structural parameters of DWPT sprinkler head.Through the combination of theoretical analysis,experimental verification and performance evaluation,the orthogonal test and hydraulic characteristics of DWPT sprinkler head are studied.The distribution laws of atomized water quantity,droplet diameter,droplet velocity and kinetic energy of nozzle under different pressure and equivalent diameter of nozzle are analyzed,and the corresponding models are established according to the laws.It is of great significance to improve the spraying quality of DWPT nozzle.The main research work and contents of this paper are as follows:(1)A DWPT type atomizing spray head is designed.Four structural parameters were selected:Equivalent diameter of water inlet A is 4 mm,8 mm,15 mm,pressure B is 0.2Mpa,0.3Mpa,0.4Mpa,equivalent diameter of water outlet C is 3.45 mm,4.88 mm,5.98 mm,spray core structure D takes three flow cores,four flow cores,six flow cores,According to the four factors and three levels table,the orthogonal test was carried out,and the optimal structural parameters of the nozzle were obtained as follows: the equivalent diameter of the nozzle was 4 mm,and the structure of the nozzle core was six channels.The influence of pressure on the equivalent diameter of the nozzle needed further experimental research.The results show that the radial atomization water distribution of all nozzles is similar in shape and basically presents a normal distribution,which increases first and then decreases with the increase of the distance from the nozzles,and the maximum atomization range is 1.33 m.The order of factors affecting the atomization range is CBDA,and the optimal combination is A1B3C3D3.(2)through the Matlab software and uniformity of calculation model for the test number from orthogonal test on overlay,the distribution of radial flow calculated DWPT aproll type atomizing nozzle in different combination spacing and the combined uniformity coefficient under different combinations,and poor analysis and study of atomization range and uniformity coefficient of each factor are studied.The results show that the uniformity coefficient of all test numbers in square combination is better than that in triangle combination.In the triangular combination mode,the uniformity coefficient changed significantly and decreased with the increase of the combination spacing,while in the square combination mode,the uniformity coefficient did not change significantly with the combination spacing,and the optimal uniformity coefficient appeared at the combination spacing of 0.7～0.9R.The spray core structure has the greatest influence on the square combination mode and the triangle combination mode.The order of influencing factors is DACB and DCAB,respectively.The optimal combination is A1B2C1D3 and A1B2C3D3,respectively.(3)2DVD video raindrop spectrometer was used to conduct atomization characteristics tests on the nozzle with an equivalent diameter of 4mm and a six-channel spray core structure at an equivalent diameter of 4.88 mm and 5.98 mm,and at a working pressure of 0.2MPa,0.25 MPa,0.3MPa,0.35 MPa and0.4MPa.According to the results of orthogonal test,the uniformity coefficient of atomizing range and triangle combination mode reaches the maximum when the equivalent diameter of outlet is 5.98 mm,and the uniformity coefficient of square combination mode reaches the maximum when the equivalent diameter of outlet is4.88 mm.Therefore,it is necessary to conduct atomization characteristic test on nozzle with equivalent diameter of 4.88 mm and 5.98 mm.The results show that the atomization range of nozzle is positively related to the working pressure and the equivalent diameter of nozzle.The average diameters of water droplets with equivalent diameters of 4.88 mm and 5.98 mm are concentrated in the range of0.73-1.02 mm and 0.85-1.25 mm,respectively.The average diameters of water droplets increase exponentially with the increase of the distance from the nozzle.When the equivalent diameter of the water outlet is 5.98 mm,the kinetic energy of the single drop,the kinetic energy per unit volume and the kinetic energy intensity under all working pressures are greater than that of the equivalent diameter of the water outlet is 4.88 mm.The kinetic energy of a single droplet and the average diameter of the droplet,as well as the kinetic energy per unit volume and the distance from the sprinkler head all showed an exponential distribution.The kinetic energy intensity fluctuated slightly in the range of 0-0.6 m from the sprinkler head,and reached the maximum value near the end of the range. |
