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HighlightsThe results confirmed that the optimal combination of structural parameters was achieved with the factor combination of 25 mm length of the tube, 150 kPa pressure, 3 mm diameter of the tube, and 5 mm nozzle diameter.The influencing factors in decreasing order of importance were: working pressure, length of the tube, and nozzle diameter for coefficient of uniformity, and nozzle diameter working pressure and diameter of the tube for range.Droplet velocities from test 7 ranged between 0 and 6.0 m/s, while that from test 2 was slightly larger, ranging from 0 to 6.7 m/s under low-pressure conditions.ABSTRACT: To select the appropriate combination of the factors for the dynamic fluidic sprinkler, hydraulic performance tests at low pressure were conducted. The main structural parameters in this study were the length of the tube (L), pressure (H), the diameter of the tube (M), nozzle diameter (N), they are represented by factors A, B, C, and D, respectively. An orthogonal array with four factors and three levels was selected, and the direct analysis technique was used to analyze the test data. The droplets and velocities data of the sprinkler were obtained by a Thies Clima Laser Precipitation Monitor. MATLAB R20014a software was used to calculate the simulated coefficient of uniformity (CU). The results showed that the optimum values of the structural parameters were: the length of the tube (25 mm), the working pressure (150 kPa), the diameter of the tube (3 mm), and the nozzle diameter (5 mm). The factors affecting coefficient of uniformity and range, in decreasing order of importance were nozzle diameter, pressure, length of the tube, and the diameter of the tube. The highest coefficient of uniformity obtained was 91% when the length of the tube was 25 mm. Droplet sizes decreased with the increase of pressure. Droplet size ranging from 0.1 to 4 mm was obtained under test 7 with a mean droplet size of 0.38 mm. The study can give a reference to the operation for saving water in sprinkler irrigated fields. Keywords: Droplet, Dynamic fluidic sprinkler, Orthogonal test, Structural parameter, Uniformity, Velocity.

HighlightsA detailed study of the relationship between the velocity distribution, length of tube and nozzle sizes. Rotation speed decreased approximately linearly as the length of the tube increased.Relative error was less than 4% for validated results indicating a perfect correlation between the values of numerical simulation, calculated, and experiment results. Abstract.A detailed study of the relationship between velocity distribution, length of tube and nozzle sizes was conducted using a dynamic fluidic sprinkler. Therefore, the objectives of this article were: (1) to study inner flow characteristics of dynamic fluidic sprinkler, (2) to compare numerical simulation and experimental results (3) to introduce an empirical equation of the variation trend of rotation speed for the newly designed sprinkler. A mathematical model for simulation of the inner flow distribution of the sprinkler was obtained by using computational fluid dynamics. The results were validated by numerical simulation and compared to the experimental results. The minimum average deviation between the calculated, simulation and experiment was 0.25%, whiles the maximum was 0.90%. It was found that the relative error was less than 4% results indicating a perfect correlation between the values of numerical simulation, calculated and experiment results. It was established that the rotation speed decreases approximately linearly as the length of the tube increases. The results revealed that the nozzle diameter, length of the tube, and the operating pressure had a significant influence on the rotation speed of the sprinkler. This study provides baseline information to improve water application efficiency for crop production in sprinkler irrigated fields. Keywords: Dynamic fluidic sprinkler, Inner flow, Nozzle, Numerical simulation, Water saving.

An impact sprinkler with a newly designed nozzle-dispersion device and R33 sprinkler were introduced in this study. Comparative experiments and analyses on uniformity patterns of impinging water jet from both sprinklers were investigated by using high-speed photographic technique to visualize the spray. A mathematical model of the spray was developed and applied in MatLab to determine the spray angles at different axial distances. Results showed that the impact sprinkler with the nozzledispersion device combination gave the largest spray range of 12.6% larger than the R33 sprinkler. Combined effect of the nozzle-dispersion device for the impact sprinkler had a strong effect on the spray angle which increased with increasing pressure. Spray characteristics for the impact sprinkler were similar to those produced by the R33 sprinkler. The number of droplets increased with increasing spray angle due to early breakup of the jet, which is beneficial for greater water dispersion and uniformity. It was found that a low working pressure of 150 kPa leads to lower degree of nonuniformities for the sprinklers, and the variation coefficient were less than 10%. Obtained mathematical models of the changes in the variation coefficient was dependent upon working pressure and can be a good basis for easy management of the parameters necessary for the uniform spray distribution. Hence, the impact sprinkler with the nozzle-dispersion device can offer superior advantage of a larger spray range for better overlap and disperse more droplets for better Uniformity under low pressure conditions.

A High-Speed Photography (HSP) technique was used to investigate the breakup process and flow behavior of low-intermediate pressure water jets issued from square and triangular shaped nozzles. The non-circular orifices were designed based on the principle of equal flowrate with the same pressure in relation to the circular orifice. The breakup morphologies and boundary structures of the jets were studied under different nozzles and working pressures. Two forms of droplet formation and the process of droplet formation, in addition to the jet breakup lengths, initial amplitudes of surface waves and jet diffusion angles of different nozzles were evaluated. It was found that the jet presented a good continuity and fluidity in the initial section, and the fluid bands gradually appeared due to the air resistance and the jet break up as the disturbance intensifies. The degree of jet breakup was enhanced with the increase of pressure and cone nozzle angle. The random appearance of the fluid band structures and the dactylitic textures near the nozzles for non-circular jets appeared earlier than those produced by the circular jets. The small satellite droplets with different shapes and sizes were seen inside and outside the jet interface. Triangular jets exhibited the shortest breakup length, the initial amplitude of surface wave, and the diffusion angle of the jet at the same pressure were largest compared with square and circular jets. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular nozzles were fitted with a relative error of less than 10%, which means the fitting formulas are accurate. Keywords: Breakup length, High-speed photography, MATLAB simulation, Non-circular nozzle, Surface wave amplitude.

Relevant factors affecting the irrigation performance of large cannon sprinkler include the nozzle diameter, operating pressure, layout form, and overlapping distance, which were studied under no wind conditions. The discharge coefficient ranged from 0.96 to 0.99. A mathematical model of radius of throw was regressed and the coefficient of determination was 0.9765. The application rate was lower near the sprinkler, and the highest value occurred under the radius of throw from 4 to 6 m for each water distribution pattern. The average application rate decreased with increase in operating pressure. The average application rate increased with the increase in nozzle diameter. The increased or decreased in magnitude of average application rate under small nozzle diameter was larger than the large nozzle diameter for the same range pressure variations. The maximum CU values increased with increase in pressure under different nozzle diameter or different layouts. Triangular layout gave higher uniformities compared with square layout. The optimal CU values and spacing coefficients of large cannon sprinkler with different layouts, pressure and nozzle diameter were proposed.

Applying fertilizer through drip irrigation system is a very important method to save fertilizer and labour. Three manifold layouts (water supply in one end for transversal drip tapes (M1), water supply in both ends for transversal drip tapes (M2) and water supply in one end for longitudinal drip tapes (M3)) and four different fertilizer solution concentrations (50.00 g L−1 (C1), 66.67 g L−1 (C2), 100 g L−1 (C3) and 200 g L−1 (C4)) were selected to investigated the effect of the manifold and concentration on water fertigation uniformity. Results showed that the emitter at the extreme end of the manifold needed more time to clean the rudimental fertilizer in the drip tapes. The minimal flushing time increased from 8 to 13, 4 to 7 and 7 to 12 min with increasing the fertilizer concentration from C1 to C4 for M1, M2 and M3, respectively. The drip irrigation system needed more time for flushing to reduce the risk of emitter clogging when a higher fertilizer solution concentration was applied. In order of performance, M2 had the highest water and fertilizer uniformity, followed by M3 and lastly by M1. The fertilizer solution concentration had no significant effect on water distribution. However, it had a significant effect on fertilizer distribution. The mass of the applied fertilizer for the drip tapes close to the inlet increased with increasing fertilizer solution concentration from C1 to C4, which indicated that higher fertilizer solution concentration can result in lower fertilizer distribution uniformity. There was a significant effect of the manifold layout on water uniformity. The fertilizer concentration and the interaction between manifold layout and concentration had no significant effect on the water uniformity. Similarly, both the manifold layout and concentration had a significant effect on fertilizer uniformity. The interaction between manifold layout and concentration had a significant effect on the Christiansen’s uniformity (CU) and distribution uniformity (DU) for fertilizer, whilst, a significant effect on emission uniformity (EU) was not found. The manifold layout and fertilizer solution concentration should therefore be considered in the design and operation of fertigation system.

The world is increasingly experiencing water scarcity due to the impact of climate change, a phenomenon that is affecting agricultural production, particularly in tropical regions. An effective response system is required to adapt and reduce the impact on agricultural production. There have been calls on the role agriculture can play to reduce the impact without compromising food security. Hence, the present article discusses some of the major difficulties in water-smart sprinkler irrigation to adapt to the impact of climate change on agricultural production. In order to meet investment cost with water-smart sprinkler irrigation, the fixed water dispersion device for an impact sprinkler needs to be optimized to improve its performance under low pressure conditions. This is necessary to produce the desirable droplets sizes for minimising evaporation losses and distortion by wind, whilst maintaining the large distance of throw. Further research should be backed by strong institutional support towards a wide-scale adoption of water-smart sprinkler irrigation technologies. This could be of significant benefit to better water management in the artificially drained catchments and lessen the impact of climate change on agricultural production.

The proportional injector is commonly used in agricultural chemigation due to its relatively high injection ratio. A major challenge with the proportional injector is related to its dependence on differential pressure, which is significantly influenced by changes in the viscosity, and setting injection ratio. A series of experiments were conducted to investigate the influence of differential pressures, solution viscosities, and setting injection ratios on the inlet and injection flow rates of a D25RE2 proportional injector. A mathematical model was developed to represent the hydraulic performance of this proportional injector. Finally, the mathematical model was verified using four different kinds of chemicals (humic acid, urea ammonium nitrate 32% N, fosthiazate, and colza oil). The inlet flow rate increased significantly with increasing differential pressure and decreased with increasing setting injection ratio. Results showed that the highest operating differential pressure should not be greater than 0.15 MPa for the D25RE2 proportional injector. The inlet flow rate gradually decreased with increasing viscosity, and a quadratic function relationship was derived between the inlet flow rate and the viscosity. The injection flow rate decreased with increasing viscosity. However, the viscosity had a slight influence on the injection flow rate when it was lower than 20 mPa·s. Mathematical models for calculating the inlet and injection flow rates with the influence of viscosity were developed, respectively. The coefficient of determination and the root mean square error (RMSE) for inlet flow rate calculation model were 0.8316 and 143.36 kg h-1, respectively. The coefficient of determination and the RMSE for the injection flow rate calculation model were 0.9706 and 0.9520 kg h-1, respectively. The calculating formula of inlet flow rate had a satisfactory accuracy under low differential pressure and high setting injection ratio. The calculating formula of the injection flow rate had a good accuracy, which is useful for calculating the injection flow rate when injected with different kinds of solutions. The average deviations between calculated and experimental injection flow rates with injection ratios of 0.2%, 1.2%, and 2% were obtained as 4.96%, 4.66%, and 4.1% respectively, which indicated that the average deviations decreased with increasing setting injection ratio. Results from this study are useful for both designers and users to effectively manage agricultural chemigation system with the proportional injector. Keywords: Agriculture, Chemigation, Proportional injector, Hydraulic performance.

The service life and stability of the large cannon sprinklers depends on the stress distribution that occurs on the drive spoon caused by the impact force of the driving water jet. A simple theory of the forces caused by the impact of the water jet on the drive spoon was developed, and a three-dimensional (3D) model numerical simulation using computational fluid dynamics (CFD) was constructed. An experiment was carried out to verify the accuracy of the simple momentum-based theory and the numerical CFD simulations. The results showed a large deviation between the simulated and measured values under low pressure conditions, with a maximum deviation of 15.98%. However, the simulations had good accuracy under high pressure conditions. The difference between simple theory and experimental values also decreased with increasing working pressure when considering both horizontal and vertical components. The simple theory was adjusted by the use of correction factors that were regressed with working pressure using experimental data. The coefficient of determination of the correction factor expressions for both the horizontal and vertical components were 0.9799 and 0.9289 respectively. After adjustment of the simple theory, the calculated values of the vertical and horizontal impact forces were compared to the experimental values and had a difference

Soybeans threshing is traditionally done by hand beating with a wooden stick on a hard surface which is a drudgeries operation which leads to time-consuming, grain damage and grain loss due to shattering for small-scale farmers. Therefore, a soybeans manual thresher (Pedal operated) machine attached to a blower was designed, manufactured and its performance evaluated to help eradicate this problem by reducing labor, improve post-harvest, and increase income to small-scale farmers. The thresher consists of a hopper, drum, shaft on bearings, frame, beaters, blower, chain, and sprocket power transmission, pedal and seat. The thresher was fabricated with sheets and angle iron and the mechanism is based on a combination of impact, compression, and shear. Two levels of moisture content level were combined to evaluate the performance of thresher in terms of its capacity, threshing efficiency and percentage grain damage. The combination of dried and wet sample mixture at a feed rate of 25kg yielded maximum threshing capacity of 96 kg/hr, 98.6% maximum threshing efficiency and minimum percent grain damage of 3.5% results was recorded, which was very satisfactory.