Improving the hydraulic performance of aerated irrigation pipeline

The micro-irrigation aeration pipe network's ambiguous hydraulic characteristics are a critical factor limiting its further application in the agricultural field. To explore the variation law of hydraulic performance of a non-outlet pipe along aeration, the experiment was conducted to evaluate 24 working conditions consisting of eight kinds of aeration volume (0, 0.20, 0.42, 0.58, 0.75, 0.92, 1.08, and 1.33 m3/s) with three levels of pipe pressure heads (11, 17, and 22 m). On this basis, the theoretical formula of influencing factors of the head loss along the non-outlet pipe was studied using the volumetric stiffness analysis method, and the calculation method was established by combining the test data. At the same time, the hydraulic performance evaluation model of the aeration pipeline is based, and the optimal aeration irrigation condition is determined by principal component analysis. The results show that the water–gas ratio serves as a key regulating parameter in the gas-filling pipeline, and the flow coefficient can be increased by increasing the water–gas ratio, and the conveying energy of the aeration pipeline can be enhanced. The calculation model of the gas-filled pipeline's average flow, amplitude attenuation, and head loss is established. The results were satisfactory through theoretical analysis and experimental verification. The hydraulic performance of the gas-filling pipeline is better than that of other treatments when the main pressure water head was 22 m and the water–gas ratio was 1.442–3.810. The findings of this study provide valuable insights into the development of aerated irrigation pipelines worldwide.