| The research in this research is supported by the National Science and Technology Support Program-“The research on the water saving irrigation technology and yield increasing with different type of water(No.2015BAD22B01-02)”,and International Cooperation Ministry of Science and major projects-“The research and application of key technology on improving water use efficiency in agriculture irrigation in arid area(No.2014DFG72150)”.With the shortage of the current water resource in the agriculture irrigation,the promotion of water-saving irrigation technology such as large movable sprinkler irrigation is the main trend to relieve the pressure of water resources crisis in agriculture irrigation.In general,the working pressure of large movable sprinkler irrigation systems is higher,and the working pressure of sprinkler installed in these systems is larger than 100 kPa.Considering the overall consumption of energy,the development of low-working pressure sprinkler irrigation system and lowe-working pressure sprinkler have been commonly focused on.T he paper selecting fixed spray plate sprinkler as the research object,the hydraulic performance are analyzed with the methods of experimental analysis and theoretical calculation.In order to improve the problems of concentrated water distribution,the structure of the grooves in the plate have been optimized.In order to deal with the problem of bad water distribution of single moving sprinkler,a new type of lower working pressure of fixed spray plate sprinkler has been developed using the theoretical calculation,and the sprinkler hydraulic performance have been analyzed.The results of the study are as follows:(1)A in door experiment of Nelson D3000 sprinkler hydraulic performance has been conducted,the result shows that the diffusion of water application rate and droplet kinetic energy are facilitated by increasing the working pressure and mounting heigh because of the acceleration of jet water crush.When the sprinkler working pressure is low in the process of irrigation,the peak water application and droplet kinetic energy rate is obvious in reducing as the increasing of sprinler mounting height.Although the increase of sprinkler working height can decrease the peak water application and droplet kinetic energy rate,water and its kinetic energy spray from one dividual groove still concentrate the location of 0.75 times of spray distance from the sprinler.When the peak spray water or kinetic energy pass through the territory of some fixed points,plants and soil can be injured by the large shock force.In order to relieve the strike damage to the plants and soil caused by the peak water application and droplet kinetic energy rate,lower working pressure sprinkler with smaller peak water application and tiny droplet kinetic energy rate and showed be developed.(2)Little research about water distribution simulation software of fixed spray plate sprinkler was done for years.To solve this problem,experimental techniques based on droplets photography have been employed to obtain the droplet velocity and angle of the Nelson D3000 spray plate sprinkler under different working pressures and different nozzles diameter,and mathematical models of spray velocity and angle were built.On these basis,ballistic simulation and droplets dynamics and evaporation models was appended in order to develop the simulation software of water distribution of individual spray Using Java-Eclipse software development tools.The software can calculate droplet size distribution,water distribution,kinetic energy distribution and water evaporation loss of the sprinkler when the operating environment was given.Hydraulic characteristics of the Nelson D3000 spray sprinkler at different operate conditions were simulated using this software,and the comparisons of measured and simulated value were taken to validate the accuracy of the software.The result shows that the variation laws of droplets distribution and water application which were simulated were similar to the measured,indicating a relatively high precision.The software can provide technical guidance of optimal design of linear-move sprinkler machines.(3)In order to improve problems of peak application of fixed spray plate sprinkler,lower working pressure sprinkler show be developed.In the processing of sprinkler exploitation,5 types cross profile of the groove including rectangle,Y,V,puerto and pentagon type were selected.Hydraulic characteristics of each treatment were analyzed,and take lowest peak applicatino rate and longest jet distance as optimizing targets,the type of Y cross profile groove was selected.And then take the number and jet angles of the grooves as the design factors,25 sprinklers was developed using laser rapid prototyping technology.The equation of jet distance and peak application rate about groove number and jet angle were regressed under different working condition,then the optimum of groove number and jet angle were calculated,the peak application is lowest and the jet distance is longest when the groove number is 27,jet angle is 18.9°.And the comparisons of measured and calculated value were taken to validate,the result shows high agreement,the parameters of the groove structure can be used to design the sprinkler with working pressure is lower than 100 kPa.And the sprinkler with 18.9°jet angle and 27 grooves was developed,the water distribution experiment of this sprinkler with moving condition was conducted,the result show that the water distribution changes sharply perpendicular to the sprinkler moving direction,the angles arrangment should be optimize further.(4)In this study,The theoretical model's validity was verified in an indoor experiment using a Nelson D3000 FSPS in motion with 36 grooves and blue-plate spray heads.In addition,based on the simulated water distribution patterns of a sprinkler in motion with different working pressures,mounting heights,and sprinkler spacings,water distribution uniformities were calculated and recommendations were made to achieve optimum water distribution uniformity.In the process of designing the angle of any two grooves,we developed and validated the theoretical basis for determining the water distribution pattern of a sprinkler in motion using water distribution data from a single sprinkler groove and applying a superposition method.The software of water distribution with moving sprinkler using Java-Eclipse development tools was developed,and triangle water distribution pattern was choosed as optimization goal in the process of trial computation using the software,the result of angles arrangement is 24°?35°?46°?57°?68°?79°?90°?101°?112°?123°?134°?145°?156°?191°?202°?220°?240°?252°?264°?276°?288°?300°?320°?338°?349°and 360°.Indoor water distribution experiment of moving sprinkler was conducted,the measured water distribution data has reached the aim of the design,this sprinkler can be installed in the moving sprinler irrigation systems.(5)In order to the obtain hydraulic performance of the lower-working pressure sprinkler,a series of indoor experiment were conducted to measure the range of the spray droplet,peak application rate and spray distance,the result shows that compared with Nelson D3000,the maxmum droplet jet from designed sprinkler is smaller,peak application rate is lower and jet distance is longer,the spray water strike damge to the plant and soil can be bring down.The coefficient uniformity and wind drift and evaporation losses of designed sprinkler and Nelson D3000 under different working condition were simulated using the designed software.the result shows that the Cu of designed sprinkler is higher than Nelson D3000 sprinkler,however the droplet jet from the designed sprinkler is samller which caused a higher wind drift and evaporation losses,so windless environment is suggested during irrigation when using the designed sprinkler to prevent high wind drift and evaporation losses. |
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