The effect of fertilizer injection on the mixing patterns of lateral-move sprinkler irrigation systems with double wings

In irrigation systems, water–fertilizer mixing within pipelines profoundly affects the fertilization process and strategy development. Taking irrigation machine pipelines as the research object, a numerical simulation method is used to investigate the mixing and distribution patterns of water and fertilizer in pipelines under a steady oscillatory flow fertilization mode with different injection positions, angles, flow rates (Q) and fertilization ratios (δ). Increasing the flow rate initially increased the fertilizer concentration in the lateral pipes, but further increasing the mainline central injection flow rate significantly reduced the concentration in the lateral pipes. For δ = 2%, elevating Q from 6 to 8 m³/h increased the average fertilizer concentration in the lateral pipes by 0.4%. However, a subsequent increase to Q = 10 m³/h led to a 1% decrease. In left-side injection, lateral pipes on the same side as the injection pipe had considerably higher concentrations than those on the opposite side. In central injection, larger inclination angles increase the lateral pipe fertilizer concentration, while in left-side injection, 60°-downward injection results in the best lateral pipe fertilizer concentration. The above-mentioned results can provide valuable insights for the design of injection ports on lateral-move sprinkler irrigation systems.