Hydraulic performance characteristics of impact sprinkler with a fixed water dispersion device

One way to adapt to the trend towards low-energy and to improve the hydraulic performance of the impact sprinkler under a low pressure condition is by means of a fixed water dispersion device.A fixed dispersion device disperses jet flow from the nozzle continuously.The shape of the tip,impact angle(θ),diameter(D),and depth in the jet flow(d)have significant influence on the hydraulic performance.In this study,the hydraulic performance characteristics of impact sprinkler as affected by the fixed water dispersion device were studied under indoor conditions.Radial water distributions from the sprinkler were obtained by experiments for the fixed water dispersion devices.MATLAB was used to transform the radial data into net data,and the uniformities were simulated in a square layout from 1 to 2 times the range(R).The droplet size distributions from the fixed water dispersion devices were measured by a laser precipitation monitor(LPM).Results showed that the range increased with the increase of pressure,and the sprinkler with type C_(2) produced a rectangular-shaped water distribution pattern,while the range was maintained.A maximum uniformity of 71.56%,75.56%,77.23%,73.32%,78.88%and 86.67%was found for types A1,B1,C1,A2,B2,and C_(2),respectively under a pressure of 200 kPa.The uniformity from the sprinkler using type C_(2) surpassed 80%,while type C1 fell below.Droplet sizes from type C_(2) was best,and the mean droplet diameter decreased with the increase of pressure.Hence,type C_(2) can be selected for further optimization of the design features to improve the hydraulic performance of the impact sprinkler under low pressure conditions.

Range formula based on angle of dispersion and nozzle configuration from an impact sprinkler

Jet breakup and dispersion from impact sprinkler are mainly influenced by the configurations of nozzle and dispersion device.Based on the structure,different types of nozzles were designed and tested with a pointed tip dispersion device under low pressure conditions.Experiments were performed using High-Speed Photographic technique,and Matlab computation program was established and applied to determine the initial jet breakup length and angle of dispersion from the nozzles.The sprinkler range decreased with the increase in diameter of nozzle,and the largest range of 15.1 m was produced from sprinkler with 6 mm nozzle size under a pressure of 150 kPa.The angle of dispersion decreased with the increase of jet velocity,the spray coverage from sprinkler with 6 mm nozzle size was 1478 mm under 150 kPa,and was not statistically different when the pressure was increased.A new range formula was established for sprinkler with dispersion device through curve fitting of the parameters of initial jet breakup length,angle of dispersion,nozzle size and working pressure.The new formula was reliable for calculating range with a relative error less than 3%.Since the formula is based on the angle of dispersion,it could be useful to estimate uniformity of water distribution in sprinkler irrigated fields.