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چكيده انگليسي :

75 Simulation Fabrication and Evaluation of a Variable Rate Sprinkler Hanieh Roshan h roshan@ag iut ac ir April 2013 Depatment of Farm Machinery Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Sayed Jalil Razavi jrazavi@cc iut ac ir AbstractWater crisis is a challenge in today world which requires different countries to manage water sources inan efficient way Human activities in watersheds inappropriate applications and crop pattern changesbesides population and water demand growth has severely limited water sources in recent decades beingone of the major factors for advent and increment of drought Regarding the necessity of agriculturedevelopment as the food supplying section of the society the use of modern and water efficient irrigationsystems is essential Sprinkler irrigation is one of the pressurized irrigation methods which increaseswater consumption efficiency along with reduction of labor cost due to more uniform distribution ofwater across the field Precision farming is a new branch of agriculture based on the site specific use ofinputs according to soil plant and microorganism needs One of the inputs for agricultural production iswater which is getting more and more limited because of cultivated area increase from one hand anddecrease of rainfall and underground water levels from the other hand Thus the efficient use of watersources based on the variable rate irrigation is considered to be a basic approach of precision farming The main purpose of this study was to design and fabricate an intelligent variable flow sprinkler applicable in solid set sprinkler irrigation system with removable sprinkler The preliminary drawing ofthe proposed sprinkler was simulated based on the dimensions of available sprinklers using Fluentsoftware The actual sprinkler was then fabricated and field evaluated To measure performanceparameters of the sprinkler it was evaluated at three pressure levels three plunger positions and threediameters of nozzle opening The software could properly simulate flow variations resulted fromdifferent pressures plunger positions and nozzle diameters Simulation results of outlet flow and pressurefor the 8 mm nozzle were more compatible with those of sprinkler field evaluation According to theobtained results of outlet flow and pressure plunger position of D3 was introduced to be the best status The sprinkler outlet flow rate indicated an ascending trend as water pressure increased and the crosssection of water extended as a result of plunger displacement However the sprinkler coefficient Kd and distribution intensity I decreased as the pressure increased In field evaluation of the sprinkler the 8mm nozzle together with plunger position of D2 and the pressure of 6 bars presented the longestsprinkling diameter The least pressure drop on the nozzle head was observed with 8 mm nozzle in D3position of plunger With 12 mm nozzle and plunger position of D2 at water pressure of 6 bar themaximum flow rate was reached It was also revealed that the variable rate sprinkler could effectivelyvary the flow rate through different plunger displacements Simulating the sprinkler in rectangular andtriangle arrangements plunger position D3 indicated the highest Du and Cu values The best uniformitywas observed in 23 23 m distance of sprinklers in rectangular arrangement In triangle arrangement testwith a 10 mm nozzle pressure of 6 bars and plunger position of D3 uniformity and overlap in 30 30 mdistance of sprinklers were 84 and 40 respectively Keywords variable rate sprinkler precision farming irrigation simulation

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شبيه سازي، ساخت و ارزيابي يك آبپاش نرخ متغير

كشاورزي دقيق , آبياري , شبيه سازي