Hydraulic performance evaluation of sand-filled dripper (SFD)

Document Type : Original Article

Authors

Department of Water and Irrigation Systems Engineering, Faculty of Agricultural Engineering, Al-Azhar University, Cairo, Egypt.

Abstract

Sand-filled dripper (SFD) is a new emission device. It is a polyethylene micro tube with diameter of 4, 6 and 10 mm and length of 10, 15 and 20 filled with sand grains of uniform diameter of 0.2, 0.8 and 1 mm. The micro tube is closed from both ends by screen pieces. The ultimate objective of this study is to reveal the reacts of on-line sand filled drippers hydraulic performance arising from the differences in the production process and the different technical features to flow variations, where the SFDs were produced at different flow rates and technical features. Twenty-seven sand-filled drippers were produced, each dripper having different technical specifications. These sand-filled drippers were divided into three types according to diameter of the micro tube from which the dripper was made. Discharge rates from the three different types were collected at five different levels of operating pressure (P). SFDs were tested at 50, 100, 150, 200, and 250 kPa pressure values. To determine the flow regime of every SFD, discharge-pressure relationship, the drippers discharge exponent (x), the coefficient of variation of the discharge (CV), the emission uniformity (EU), and the dripper flow variation (qvar) were evaluated at the different operating pressures. Results of the research have been proved that discharge-pressure relationship of on-line sand-filled drippers is in directed proportionate. As that the flow regime for all SFDs of type 4 are laminar flow and unstable flow regime for all SFDs of types 6 and 10. The results showed that the discharge rate of all types of sand-filled drippers generally increases with increasing the operating pressure. Values of Cand EU of all considered sand-filled drippers at different operating pressures concluded that the drippers are of good quality. This study introduces a new idea for control technology of trickle irrigation systems.

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