عنوان مقاله [English]
Sprinkler droplet diameter is one of the affecting factors on the application radius, wind drift and evaporation losses, soil compaction and generally it is sprinkler quality indicator. Determination of the proper drop diameter helps the efficient sprinkler selection to meet technical and design goals. In this research, the intelligent Gene Expression Programing (GEP) method was applied for modeling of mean drop diameter emitted from impact sprinklers. Model input data were included nozzle diameter, operation pressure and distance from sprinkler; and model output was mean drop drop diameter landed at the certain distance from sprinkler. For preparing model inputs, experiments were conducted for 22 nozzle size and operation pressure combinations and considering 9 to 14 spatial steps of 1.5 m intervals. Using digital photographic method and analyzing the photos, the drops drop diameter data were obtained under all experimental conditions. In addition, sprinklers application radii were measured in the experiments. Consequently, by classification of nozzle sizes, operation pressures, measuring distances on one hand and mean drop drop diameters on the other hand and application of GEP method, a model was developed to predict mean drop size in the different distances from sprinkler. Comparisons between model results and observation data showed high accuracy of the proposed model with R2=0.91 and RMSE= 0.402. In addition the simultaneous effects of pressure and nozzle diameter on drop drop diameter were investigated in this research.