الفهرس 
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Abstract
DROPlet size and water application patterns data from the sprinkler fitted with nozzles shapes (square, rectangle, triangle and circle) were studded. A total of 48 experiments were carried out (i.e. 4 pressure levels × 4 orifice shapes × 3 replicates) to study the effect of the nozzle shapes and operating pressures on DROPlet size distribution. Another 48 experiments were conducted using same treatments for the water distribution uniformity experiments. The pressure range was between 138 kPa and 241.5 kPa at 34.5 kPa increment. DROPlet size diameters were measured using the immersion method and Image Pro software. A finite difference numerical model was developed to determine the mean DROPlet size diameter at any distance from a sprinkler as a function of nozzle shape and pressure. DROPlet size data from circular and noncircular nozzle orifice shapes verified the model. The computer model was also used to study the effect of wind speed and direction on irrigation pattern. Increasing wind speed elongates the pattern at right angles to the wind, increases the wetted distance downwind from the sprinkler and decreases the wetted distance upwind. The increase was proportionately less than the decrease in wetted distance upwind. Therefore, the wetted area is inversely proportional to wind speed. Nozzle pressure and shape had a major influence on DROPlet size. The DROPlet size inversely proportional to the pressure. Higher pressure promoted smaller DROPlets over the entire application profile especially near the perimeter. Using noncircular orifice nozzle increases the diameter of the small DROPlets falling near the sprinkler. At the same time, it decreases the diameter of the largest DROPlets near the wetting circle edge. This may be interpreted on the basis that circular nozzle increases the throw. Consequently, increasing the diameter of the small DROPlets would in fact help on decreasing wind drift and evaporation loses. Meanwhile, decreasing the diameter of the large DROPlets would reduce the possibility of soil crust. Noncircular nozzles have the advantages of providing an acceptable water application pattern over the entire precipitation profile at low operating pressure. Noncircular nozzles were compared to circular nozzle for water application profiles. To simulate the water application profile for two sprinklers overlapped at 100%, the Excel program was implemented. The application profiles for non circular nozzles were compared with circular ones. The over irrigation for the sprinkler wetted circle was calculated. It was higher for circular nozzle than all shapes of noncircular nozzles. To calculate the distribution uniformity (Cu), four sprinklers were virtually assumed to have a square spacing pattern overlapped at 100%. The results recommend using noncircular nozzles instead of circular nozzle shape especially triangular and rectangular orifice shapes for to rationalize energy.