CFD-DEM coupling simulation and parameter optimisation of sugarcane harvester extractor

Abstract

The impurity removal process of sugarcane mechanised harvesting by extractor faces the challenge of high impurity content and cane loss. To improve the impurity removal performance of extractor and explore the internal flow field and material movement, the impurity removal process was simulated using the computational fluid dynamics (CFD) and discrete element method (DEM) coupled method. The results revealed that the large-sized depression at the installation site of the hydraulic motor, along with variations in the blade profile at the leading and trailing edges, and the short length of the cleaning chamber, contributed to a wide range of vortex and flow separation, which made the material move in disorder and easily discharged from one side of outlet, reducing the impurity removal efficiency. With the number of blades, installation angle, and chord length as factors, and velocity and number of leaves as the indicators, a Box-Behnken experiment was conducted to optimise the extractor parameters. The results showed that, at speeds of 1250, 1450, and 1650 r min⁻¹, the average outlet airflow velocity increased by 11.9%, 14.6%, and 19.9% respectively, the total pressure increased by 33.94%, 34.33%, and 25.19% respectively, and the extractor efficiency increased by 34.88%, 36.96% and 39.65% respectively. The improved extractor significantly reduced the impurity content while maintaining a stable cane loss at high travel speeds (3 km h⁻¹), the corresponding reduction rates at the three speeds were 20.9%, 23.9%, and 18.0%. The research will contribute to guiding the design and optimisation of sugarcane harvester extractors.