Simulating water distribution patterns for fixed spray plate sprinkler using the ballistic theory

Abstract

Ballistic simulation of the spray sprinkler for self-propelled irrigation machines requires the incorporation of the effect of the jet impact with the deflecting plate. The kinetic energy losses produced by the jet impact with the spray plate were experimentally characterized for different nozzle sizes and two working pressures for fixed spray plate sprinklers (FSPS). A technique of low speed photography was used to determine drop velocity at the point where the jet is broken into droplets. The water distribution pattern of FSPS for different nozzle sizes, working at two pressures and under different wind conditions were characterized in field experiments. The ballistic model was calibrated to simulate water distribution in different technical and meteorological conditions. Field experiments and the ballistic model were used to obtain the model parameters (D50, n, K1and K2). The results show that kinetic energy losses decrease with nozzle diameter increments; from 80% for the smallest nozzle diameter (2 mm) to 45% for nozzle diameters larger than 5.1 mm, and from 80% for the smallest nozzle diameter (2 mm) to 34.7% for nozzle diameters larger than 6.8 mm, at 138 kPa and 69 kPa working pressures, respectively. The results from the model compared well with field observations. The calibrated model has reproduced accurately the water distribution pattern in calm (r=0.98) and high windy conditions (r=0.76). A new relationship was found between the corrector parameters (K1’ and K2’) and the wind speed. As a consequence, model simulation will be possible for untested meteorological conditions.

Effect of intra-irrigation meteorological variability on seasonal center-pivot irrigation performance and corn yield

“…As the nozzle diameter increases, the parameter D 50 increases. Similar trends but with slightly lower values for this parameters were presented by Ouazaa et al 2014 for FSPS.…”

“…2b). Ouazaa et al (2014) characterized the kinetic energy losses in FSPS (Fixed Spray Plate Sprinkler) reporting similar trends. The smallest nozzle diameter evaluated of FSPS, 2 mm, resulted in kinetic energy losses of 80%.…”

“…The selection of the drops was performed based on image quality since the drop should be adequately focused (located near the vertical plane containing the reference ruler). Main difference between drop velocity at the nozzle and after the impact was attributed to the energy losses at the plate (Ouazaa et al 2014).…”

“…The ballistic model approach was used in this study to simulate the water distribution pattern of the RSPS for different nozzle diameter and wind conditions. The calibration process of the model parameters (D 50 , n, K 1 and K 2 ) is described in Ouazaa et al (2014). D 50 (mean drop diameter) and n (dimensionless exponent) are the parameters of the exponential model that characterize the drop diameter distribution (Li et al, 1994).…”

Characterization and Simulation of a Low-Pressure Rotator Spray Plate Sprinkler Used in Center Pivot Irrigation Systems

“…A number of simulation models have been developed based on experimental data in order to improve the sprinkler irrigation designs. The characterization and simulation of the spatial water distributions patterns, the energy losses, the drop size distribution, and the wind drift and evaporation losses for FSPS and RSPS have been subject of numerous studies [9][10][11][12][13][14].…”