An experiment was conducted to determine the effects of pressure loss, combined spacing, and.

A model of a linearly moved irrigation system (LMIS) has been developed to calculate the water application depth and coefficient of uniformity (CU), and an experimental sample was used to verify the accuracy of the model. The performance testing of the LMIS equipped with 69-kPa and 138-kPa sprinkler heads was carried out in an indoor laboratory. The LMIS was towed by a winch with a 1.0 cycle/min pulsing frequency while operating at percent-timer settings of 30, 45, 60, 75, and 90%, corresponding to average moving speeds of 1.5, 2.3, 3.3, 4.0, and 4.7 m min⁻¹, respectively. The application depth and CU obtained under various speed conditions were compared between the measured and model-simulated data. The model calculation accuracy was high for both operating pressures of 69 and 138 kPa. The measured application depths were much larger than the triangular-shaped predictions of the simulated application depth and were between the parabolic-shaped predictions and the elliptical-shaped predictions of the simulated application depth. The results also indicate that the operating pressure and moving speed were not significant factors that affected the resulting CU values. For the parabolic- and elliptical-shaped predictions, the deviations between the measured and model-simulated values were within 5%, except for several cases at moving speeds of 2.3 and 4.0 m min⁻¹. The measured water distribution pattern of the individual sprinklers could be represented by both elliptical- and parabolic-shaped predictions, which are accurate and reliable for simulating the application performances of the LMIS. The most innovative aspect of the proposed model is that the water application depths and CU values of the irrigation system can be determined at any moving speed.

In this study, five locally produced different V-cut flat fan nozzles named A2, B2, C2, D2 and E2 were introduced for experimental investigation on their effect on spray characteristics. The results were collected about droplet size, spray volume distribution, spray angle, sheet length, velocity, Weber number and discharge coefficient experimentally at pressures of 100 kPa, 200 kPa, 300 kPa and 400 kPa respectively. To evaluate nozzle performance under varying pressures, each parameter had its own experimental setup. The results showed that V-cut depth greatly impacts flat fan nozzle performance. Spray angle and droplet size were both enhanced with increasing V-cut depth. The deeper cuts improved the flow dynamics, which in turn permitted the nozzle to spray at a wider angle and with finer droplets. This study reveals that as increasing the spray angle significantly improved the spray volume distribution respectively. This allows for more uniform and wide coverage. Conversely, reducing the depth of the V-cut increases the stream velocity resulted the droplets become coarser due to insufficient shear stress. When the fluid’s velocity increases too rapidly, the shear stress does not have adequate time to effectively atomize the fluid into fine droplets. While higher velocity generally enhances shear, excessive flow speed can hinder the fluid from experiencing the appropriate shear forces at the optimal moment. As a result, instead of producing smaller droplets, the fluid ends up generating larger, coarser droplets. A mathematical model was developed from the experimental data to estimate droplet size and spray angle. The model’s predictions closely match the experimental results, demonstrating the model’s accuracy. The investigation found that the optimum V-shaped cutting depths were C2, D2, and E2, as these nozzles obtained better spray angles and showed a greatly improvement droplet size and spray volume distribution.

A numerical model was developed to determine the water drop movement and mean droplet size diameter at any distance from a sprinkler as a function of nozzle size and pressure. Droplet size data from 4, 5, 6, and 7 mm nozzle sizes verified the model. Data for model prediction were generated throughout lab experiments. The results demonstrated that the correlation between the observed and predicted droplet size diameter values for all the nozzle sizes and pressures is quite good. Nozzle size and pressure had a major influence on droplet size. Higher pressure produced smaller droplets over the entire application profile. The wetted distance downwind from the sprinkler increased as wind velocity increased, for example at a constant working pressure of 300 kPa, at wind speeds of 3.5 m/s and 4.5 m/s, 20% and 32% of the total volume exceeded the wet radius respectively. Larger droplets (3.9–4.5 mm), accounting for 3.6% and 6.3% of the total number of distributed droplets, respectively. The model can also predict the droplet size distribution at any wind direction overall the irrigated pattern.

In sprinkler irrigation systems in hilly areas, pressure-regulating devices can improve the uneven pressure distribution on branch pipes and consequently improve the irrigation uniformity. A pressure-regulating device for sprinkler irrigation systems was developed; the variation characteristics of the internal pressure field and velocity field distribution over time, variation law of the elastic diaphragm of the pressure-regulating device with respect to the inlet pressure, and pressure-regulating and flow stabilizing mechanisms were assessed. The results show that the pressure regulation and flow stabilization of the pressure-regulating device were affected by the deformation of the elastic diaphragm. When the elastic diaphragm deforms, the main factors of pressure regulation and flow stabilization in the pressure regulation device gradually shift from the side channel and compensation chamber to the side channel and secondary channel. The channel structure plays a crucial role in the entire fluid system. A comparison and analysis of the changes in cross-sectional pressure and flow velocity of the flow channel under different inlet pressures revealed that increasing the height of the side flow channel baffle and auxiliary flow channel effectively improved the pressure-regulating and flow-stabilizing performance of the pressure-regulating device. The results can be useful to optimize the structure of pressure regulation devices and to solve the problem of excessive pressure deviation in sprinkler irrigation systems in hilly areas.