Synergistic effects of rated flow rate and sediment size distribution on clogging in pressure-compensating emitters: Mechanism analysis

Sediment-laden drip irrigation is an important approach for alleviating agricultural water shortages, but emitter clogging seriously restricts the service life of drip irrigation systems. Unlike previous studies that mainly focused on single-factor effects, this study investigated the synergistic effects of emitter rated flow rate and sediment particle-size distribution on the clogging behavior of the tested PCJ-type on-line pressure-compensating emitters. Three commonly used emitter rated flow rates, namely 2, 4, and 8 L·h−1, were selected. Three sediment particle-size distributions were tested. Sediment particles were arranged in ascending order of particle size, and the maximum particle sizes corresponding to a cumulative volume fraction of 90%, namely D90, were 41.12, 60.77, and 80.65 μm, respectively. Emitter clogging was evaluated using multiple indicators, including average relative discharge, water application uniformity coefficient, sediment incipient motion, sediment retention in laterals, and sediment discharge characteristics from emitters. The results showed that rated flow rate, sediment particle-size distribution, and their interaction all had highly significant effects on emitter anti-clogging performance (P < 0.01). A significant crossover interaction was identified: under the fine-sediment water source condition (D90 = 41.12 μm), the 8 L·h−1 emitters had the longest service life, which was 33.33% and 18.92% longer than those of the 2 L·h−1 and 4 L·h−1 emitters, respectively. However, under coarser sediment conditions, the optimal rated flow rate shifted to 4 L·h−1. When D90 was 60.77 μm, the service life of the 4 L·h−1 emitters was 14.29% and 68.42% longer than those of the 2 L·h−1 and 8 L·h−1 emitters, respectively; when D90 was 80.65 μm, the corresponding increases were 8.33% and 62.50%, respectively. This reversal was mainly caused by the combined effects of flow-path dimensions, flow velocity, and sediment incipient motion, which jointly controlled the amount and particle size of sediment transported to emitter inlets, as well as the sediment transport capacity within emitter flow paths. These findings provide quantitative parameter support for selecting emitter rated flow rates in irrigation districts with different sediment conditions and offer a practical basis for clogging prevention and control in sediment-laden drip irrigation systems.