Study on the performance of detection air duct and evaluation index of agricultural cleaning centrifugal fans

Agricultural centrifugal fans play a pivotal role in agricultural machinery, particularly in the context of combine harvesters. The performance of these fans significantly impacts the overall operational efficiency of the machine. Given the absence of robust performance testing and evaluation methodologies for agricultural centrifugal fans, this study assesses fan performance by examining the actual air-flow dynamics in a certain space at its outlet. Subsequently, the effects of various structural parameters on airflow smoothness and attenuation are investigated by computational fluid dynamics simulation analysis. The optimal detection air duct is developed, and the measured fan performance parameters and evaluation indexes are discussed and analysed using bench tests. The obtained results indicate that the arc connection section exhibits reduced interference with the air outlet of the agricultural centrifugal fan. Additionally, the attenuation section, characterised by a diffusion angle of 4, effectively captures air attenuation properties. Minimal wind speed fluctuation is observed at the measuring point equidistant from the inlet and outlet of the steady flow section. Consequently, optimised structural parameters for the detection air duct and the specified location of the measuring point are determined. Furthermore, the performance parameters of the agricultural centrifugal fan are measured, and dimensional and dimensionless performance evaluation curves are generated based on bench testing. The fan's efficiency increases with higher air volume and flow coefficient but tends to change gradually due to the rate of increase, aligning with the expected performance of the agricultural centrifugal fan. The proposed performance detection device and evaluation method for agricultural cleaning can accurately detect the operational performance of the agricultural centrifugal fan.