Optimal structure design of a sugarcane harvester extractor based on CFD

To address the challenges of high impurity rate and cane loss rate in mechanized sugarcane harvesting, the internal flow field of the extractor was analyzed through computational fluid dynamics (CFD) simulation, and the structure of the extractor was optimized to improve the harvesting quality. The simulation model was validated by comparing simulated and experimental wind speeds at the extractor outlet, yielding a maximum error of 5.29% and an average error of 4.71%, confirming the model’s accuracy. The analysis revealed that abrupt changes in structural geometry lead to significant airflow vortices within the discharge hood, a backflow phenomenon at the outlet, and additional vortices in the cleaning chamber, all of which ultimately result in high impurity rate and cane loss rate. To address these issues, the extractor’s structure was optimized, the outer contour of the discharge hood was designed as a smooth arc curve, and the lower air inlet of the cleaning chamber was changed from rectangular to circular, which eliminated the vortices and improved airflow uniformity. The impurity rate test showed that when the harvester driving speed was 1 km/h, the impurity rate level before and after optimization was comparable across different rotational speeds. At 2 km/h, the low-speed performance (1250 r/min) was significantly improved, reducing the impurity rate by 21.52%. At 3 km/h, the impurity rate decreased by 19.84% and 28.30% at low and medium speeds (1450 r/min), respectively. The cane loss rate test demonstrated that when the extractor speed was 1250 r/min, the difference before and after optimization was minimal. At 1450 r/min, the cane loss rate decreased significantly, with a maximum decrease of 10.75%. At 1650 r/min, the cane loss rate decreased by 8.78% at most. The optimized extractor significantly reduced the impurity rate and cane loss rate at higher harvester speeds (2-3 km/h), making it suitable for large-scale and high-speed harvesting operations and improving the harvesting efficiency. The research results will help to design and improve the performance of the extractor, thus improving the harvest quality and increasing farmers’ income.