Sprinkler uniformity as affected by riser characteristics
1993
Nderitu, S.M. | Hills, D.J.
The riser height, the angle the riser makes with the vertical, and riser flexibility are important considerations in the design of solid-set and set-move sprinkler irrigation systems. Outdoor single sprinkler pattern tests were conducted to provide data for calculating design field uniformities with different riser configurations. The sprinklers were operated for four hours during the night at a 300-kPa (43.5-psi) nozzle pressure. Average wind speed over the test intervals was less than 2 m/s (4.5 mph). Data from the single sprinkler tests were mathematically overlapped to simulate complete irrigations at selected sprinkler spacings. Uniformities were compared for sprinklers operating on level terrain under negligible wind conditions for different riser heights, riser angles, and riser flexibilities. The results indicate that riser height affects water application uniformity. Precipitation profiles for impact sprinklers inclined 0 degree and 10 degrees from the vertical were similar. However, an inclination of 20 degrees negatively affected the application uniformity. Sprinklers on solidly supported risers had higher uniformities than did sprinklers on unsupported risers. Mathematical analysis found the negative effects of low riser height, non-perpendicular riser orientation, and riser flexibility could be minimized by closer spacing of the sprinklers.
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