Aerated drip irrigation is rendered as a new water-saving irrigation method based on drip irrigation technology, which is endowed with the function of effectively alleviating the problem of rhizosphere hypoxia in crop soil, enhancing the utilization rate of water and fertilizer; as a result, it improves the harvest and quality of crops. However, clogged emitters are important indexes, among others, that pose an influence to the service effect and life duration of drip irrigation systems. At present, the working principle and mechanism of the influence of air feeding on the blockage of drip irrigation emitters remain unclear. Therefore, based on the two gas filling methods of the micro/nano bubble generator and Venturi injector, the dynamic change process for the average flow ratio of an air-filled drip irrigation emitter was studied by the method of emitter plugging test. 16S rRNA sequencing was used to analyze the microbial diversity of the emitter plugs. The results show that the air injection can pose influence on the clogging procedure of drip irrigation emitters, and more importantly, it makes the distribution of blocked emitters more uniform, thus improving the uniformity of the system. Different filling methods have different effects on the blockage of the emitter. Among them, the blockage time of drip irrigation system under the micro/nano aerated drip irrigation (MAI) mode is 5.73 times longer than that under unaerated drip irrigation (UVI), and similarly, Venturi gas drip irrigation (VAI) is close to that under UVI. The filling method changed the microbial diversity of the blockage in the emitter. Among them, the number of operational taxonomic unit (OTU) unique to MAI was 2.1 times that of UVI, and the number of OTU unique to VAI was 1.3 times that of UVI. Meanwhile, gas addition will inhibit the growth of Nitrospirae and Proteobacteria microbial communities and promote the growth of Firmicutes and Actinobacteria microbial communities. Furthermore, the increase in microbial extracellular polymer in the plugging material of the emitter was inhibited and the plugging process of the emitter was slowed down. The research results are of great significance in the disclosure of the clogging mechanism of drip irrigation emitter and constructing the green, anti-blockage technology of aerated drip irrigation.
Vortex pump has characteristics of low efficiency and serious surface erosion of blade, which seriously affects service life. Therefore, it is particularly important to improve the efficiency of vortex pump and reduce erosion of blade surface. In this investigation, the design of experiment was used to determine the test plan and the number of samples tested. The relationship between geometric factors of vortex pump and efficiency and erosion rate of blade was established using the kriging approximation model. The genetic algorithm solved the multiobjective optimization and obtained the Pareto front solution using NSGA-II. The results showed that the width of nonblade cavity of the vortex pump is reduced by 18.93%, the number of blades of the impeller is increased by one, and the outlet width of the blade is increased by 19.81%. The performance after optimization is significantly improved compared with the original prototype. At design flow rate, the efficiency of the vortex pump increases by 3.24%, while the efficiency increases by 2.59% and 6.24% at 0.8Qd and 1.2Qd, respectively. The maximum erosion rate of blade surface 8.52 × 10−4 kg/(m2·s) is reduced to 7.18 × 10−4 kg/(m2·s) at 1.0Qd by optimization, which is reduced by 15.73%. The blade erosion after optimization is significantly controlled, and the angle of particle hitting blade surface is reduced.
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