Research on the influence law of the parallel fan structure of the large feeding capacity corn combine harvester on the airstream dynamics spatial characterization in the grain separation compartment

Abstract

To enhance the cleaning effect of the grain harvester under the condition of large feeding volume, and to improve the adaptability between the airstream distribution law at the sieving interface and the dispersion pattern of mixed and extruded materials, and to efficiently utilize the airstream to blow and stratify the mixed and extruded materials at the sieving interface. This study focuses on the air current source of the cleaning device − the structure of the cleaning fan itself, and combines the physical properties of the grains themselves and their dispersion pattern at the sieving interface of the upper cleaning screen to study the distribution law of the internal airstream dynamics of the grain separation assembly under the changes of various key parameters of the parallel dual fans. A multi-factor optimization test was conducted on a parallel double fan structure, considering blade width, impeller diameter, number of blades, parallel clearance, and inclination angle of the splitter plate as objective factors. The wind speed distribution in front and behind the vibrating mesh served as the evaluation index. Response surface analysis demonstrates the interaction of critical factors on wind speed distribution both sieve windward region and leeward region. The optimal combination of operating parameters is determined through the utilization of a two-index optimization method: impeller diameter 500 mm, blade width 530 mm, number of blades 10, parallel gap 90 mm, and deflector plate Angle 24°. The results under this parameter combination are as follows: The airstream velocity at the front part of the screen is 12.07 m/s, and the airstream velocity at the rear part of the screen surface is 8.13 m/s. A test bench for the parallel dual-fan cleaning device was set up, and the determination of the airflow field was carried out. The experimental data demonstrate strong correlation with numerical simulation outputs. The optimized dispersion pattern of the airflow field is compatible with the dispersion pattern of the discharged substances at the sieving interface, meeting the requirements of the cleaning operation. The optimization model of the cleaning index is reliable. The findings offer substantial guidance for refining the cleaning fan structure of the harvester.