A mesh filter is one of the key components of micro-irrigation systems, which plays an important role in filtering impurities and slowing down dripper blocking. The filter head loss tends to increase with the increase of intercepted impurities, resulting in screen breakage or forcing system shutdown. This study adopted the method of inductive analysis of literature data to carry out K-means cluster analysis on the head loss data of vertical, composite, horizontal, torpedo, flap, Y-type and hand-cranked cleaning of 7 types of mesh filters at different stages, and summarized the trend of dynamic change of head loss. Then, in order to clarify the reasons for the surge in head loss for the Y-mesh filter, the study designed three types of flow rates of 2.5, 3.5, and 4.5 m³/h, three sediment concentrations of 60, 80, and 100 mg/L and four grades of sand-containing water mainly of >54-75 ( Grade Ⅰ ), >75-100 ( Grade Ⅱ ), >100-125 ( Grade Ⅲ ), and >125-150 μm ( Grade Ⅳ) respectively, and carried out a full-scale experiment to test the effects of different flow rates, sediment concentrations, and sand grades on the head loss of the filter. With the main objectives of reducing the head loss surge and improving the sand stopping effect, a CRITIC-TOPSIS comprehensive evaluation was carried out with the evaluation indexes of increase rate of head loss during steady increase stage, increase rate of head loss during sudden increase stage, clogging uniformity, total operation time, total head loss and desanding rate to optimize the suitable operating conditions of the Y-filter. The results showed: 1) The change in different types of mesh filters head loss over time was divided into a steady increase stage and a sudden increase stage, the sudden increase in the stage of the head loss had larger growth rate and shorter operation time; The ratio of the duration of both stages was greater than 0.5, and the filter clogging uniformity was greater than 1. 2) Under the same flow rate and concentration, grade Ⅲ and grade Ⅳ were more likely to produce head loss surge than grade Ⅰ and grade Ⅱ. Under the same flow rate, the head loss surge was more likely to occur under high concentration conditions. Under the same concentration, the head loss surge was most likely to occur when the flow rate was 3.5 m³/h. 3) The results of CRITIC-TOPSIS comprehensive evaluation showed that the top three indexes affecting the hydraulic performance were 100-125, 125-150 and 75-100 μm water with the flow rate of 2.5 m³/h and the sediment concentration of 60 mg/L, and their comprehensive score indexes were 0.726, 0.712 and 0.711, respectively. The combinations of low sediment concentrations and larger particle gradations, as well as those with high sediment concentrations and smaller particle gradations, performed well at a flow rate of 2.5 m³/h. However, when the flow rate increased to 4.5 m³/h, the combinations of the higher sediment concentrations and the larger particle sizes exhibited superior comprehensive performance. In contrast, those with low sediment concentrations and small particle gradations demonstrated relatively consistent performance across all the three flow rates tested. The study can provide valuable information for reducing head loss and increasing operation time of filter.

A disc filter is one of the key components in micro-irrigation systems, and plays an important role in filtering impurities and reducing clogging of emitters. However, the disc filter cannot fully meet the filtration requirements of different impurity particle sizes, due to a single type of discs and a narrow range of sand grain sizes for filtration. In this research, a disc filter with an adjustable filter mesh size was proposed to reasonably change the tightness between discs. The disc filter also met the filtration requirements in the different ranges of impurity particle size, in order to reduce the manufacture and operation costs. A series of tests was carried out on the hydraulic performance of disc filters with different mesh. Five flow rates of 10, 15, 20, 25, and 30 m³/h were then set to test the head loss in the conditions of clear water with different mesh sizes of disc filters. In addition, the head loss and sand interception of disc filters were evaluated with different mesh numbers under different grades and contents. Three grades were selected as the small, medium, and large sandy water with less than 75, 75−150, and 150−300 μm sand particles and three sand contents of 0.8, 1.0, and 1.2 g/L. The results show that: (1) Different objectives of mesh filtration were achieved to adjust the disc tightness. Three types of discs were used to obtain 7 levels of tightness under three motor pressures, corresponding to filter mesh sizes of 50, 60, 75, 100, 120, 150, and 200. (2) There were some differences in the head loss dynamics and sand interception of the 7 mesh disc filters. In small graded sandy water, the 200-mesh disc piece shared the largest peak head loss, where all maximums were stabilized at about 16 m. The sand interceptions of the 200-mesh disc were 54, 73, and 84 g, which were significantly larger than that of others (P<0.05). In intermediate-graded sandy water, the head loss was greater than for 120, 150, and 200 mesh discs, with the maximum exceeding 6 m. The sand interceptions for 120 and 150 mesh discs were 72, 92, and 103 g, and 81, 92, and 95 g, respectively, which were significantly greater than that of the others (P<0.05). In large grades of sandy water, the 50, 60, 75, and 100 mesh discs all shared greater sand interceptions and increased head loss. (3) The optimization configuration of the filter mesh size was achieved using the TOPSIS. Therefore, a 200-mesh disc should be chosen in small graded sandy water. A 120-mesh disc should be chosen in intermediate-graded sandy water when the content was high, and a 150-mesh disc should be chosen when the content was low. A 50- or 60-mesh disc should be selected in large grades of sandy water when the content was high, and a 75- or 100-mesh disc should be chosen when the concentration was low. The best filtration was achieved to effectively avoid the hidden danger of head loss surge. The finding can provide a strong reference for the rational selection and use of disc filters under different sand contents in micro-irrigation systems, in order to reduce the head loss of the filter