Author
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Kincaid, Dennis |
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Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/9/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Sprinkler irrigation comprises nearly half of the irrigated area in the U.S.A. and the percentage is increasing. A wide range of sprinkler types is available for use on both stationary and traveling laterals, and for a wide range of operating pressure. Droplet sizes from sprinklers vary widely, and thus the mean kinetic energy varies greatly between sprinkler types. Droplet impact on the soil increases erosion potential. Selecting the optimum type of sprinkler and operating conditions for a particular soil requires knowledge of the droplet kinetic energy. A method was developed to estimate the mean kinetic energy per unit volume of water applied from the sprinkler type, nozzle size, and pressure. The effects of wind and nozzle elevation can also be estimated. The mean volumetric drop size can also be used to estimate droplet energy for other types of sprinklers if drop size information is available. The results will be useful in sprinkler selection when combined with other results on the effect of droplet energy on infiltration and erosion processes. Technical Abstract: Information on the droplet energy from sprinklers is important for choosing the optimum sprinkler type for a particular soil. Drop size distribution data were collected for a number of different types of sprinklers with different nozzle size-pressure combinations using a laser-optical method. Droplet velocities were calculated using a trajectory model. The overall droplet energy per unit of applied water was calculated. A method was developed to estimate the kinetic energy for a particular type of sprinkler with a given nozzle size and operating at a given pressure using nozzle size and pressure head as independent variables. The volume mean drop size was found to be a good predictor of overall kinetic energy. With no wind, the overall droplet energy varied from about 5 to 25 J/kg. The smooth plate spray head gave the lowest droplet energy, while the single nozzle impact-type sprinklers gave the highest. Wind was found to increase droplet energy by as much as a factor of three, but nozzle elevation has little effect on droplet energy. |
