Abstract：According to the principle of equal flow, two sorts of special-shaped nozzles with cross-sections such as square and equilateral triangle were designed, and their hydraulic performance was compared with that of the ordinary nozzle with circular cross-section. Effects of taper angle, pressure and outlet cross-section shape on flow, range, sprinkler intensity and irrigation uniformity were examined at low pressure. By using experiment and Matlab code, the combination irrigation uniformity was analyzed, these special-shape nozzles were placed in a rectangular pattern at low pressure, and the optimum special-shaped nozzle and the best combination spacing were determined in terms of the best irrigation uniformity. The results show that the flow and range of the nozzles increase with increasing pressure at a fixed taper angle. At a constant pressure, the flow and range decrease with increasing taper angle. Under low pressure conditions, the irrigation uniformity is greatly improved in the special-shaped nozzles in comparison with the ordinary nozzle. The special-shaped nozzle with outlet cross-section of equilateral triangle and 45° taper angle is the optimum nozzle in terms of the best irrigation uniformity at low pressure, and the corresponding optimal combination space is the effective spraying radius. It can be seen that the combination uniformity coefficient of the special-shaped nozzles is much higher than that of the ordinary nozzle. This fact indicates that choosing special-shaped nozzles in combination sprinkler irrigation can even better reflect the advantage in sprinkler irrigation uniformity.
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