To improve the airflow distribution consistency of each branch in the pneumatic fertilizer transportation system, so as to reduce the influence of airflow instability on the uniformity and stability of fertilizer transportation, as well as the energy waste in the process of pneumatic fertilizer transportation, a centralized pneumatic fertilizer transportation system for deep fertilization device was designed. Through theoretical calculation, the needed air flow rate, airflow speed and fertilizer pipe diameter of the system were obtained, and the fan was selected. Based on the Fluent simulation and bench tests, the influence of three air distribution method of placing fan at the end of main duct, placing fan in the middle of main duct and centralized air distribution on the airflow velocity and consistency of each branch was analyzed. The results showed that the airflow consistency of each branch in the centralized air distribution method was the best. Taking the air velocity at the outlet of each branch and its variation coefficient as the evaluation index, single factor and orthogonal simulation tests was carried out to optimize the structural parameters of centralized air distribution device. The simulation results showed that the primary and secondary factors affecting the air distribution consistency were: A (sidewall inclination angle), B (branch diameter), C (branch distance), A×B (interaction between A and B), B×C (interaction between B and C), A×C (interaction between A and C), and all the factors and their interactions had significant effects. The best parameter combination was sidewall inclination angle 15°, branch diameter 32 mm, branch distance 43 mm. With the combination, the variation coefficient of airflow velocity was 0.27% in simulation test and 1.23% in bench test. This research optimized the structure and parameters of pneumatic fertilizer transporting system, and provided references for the design and optimization of pneumatic fertilization and seeding device.
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