Optimization and experimental analysis of a cleaning device for super rice with high impurity rates based on airflow field enhancement

The harvesting process of super rice is associated with certain challenges involving the effectiveness of the harvesting equipment. To adapt the cleaning device to this process and keep pace with the performance improvements made to the separation device, the cleaning device must handle high impurity contents in the ejected material after initial separation. This paper proposes a structural improvement to the conventional wind-sieve cleaning device by incorporating streamlined arc plates with pneumatic characteristics onto the cleaning vibrating sieve, providing a dynamic airflow guidance structure to enhance the airflow distribution inside the cleaning chamber. First, indicators for evaluating the quality of the airflow field were established. Through the measurement and calculation of the airflow field, a multiobjective optimization orthogonal experiment was conducted on the working parameters affecting the airflow field. The parameter combination for the optimal performance of the cleaning device was determined to be as follows: a fan speed of 1250 r/min, first and second guide plate angles of 37° and 30°, respectively, and a fish-scale sieve opening of 24 mm. Field tests conducted to supplement the multiobjective orthogonal experiment helped confirm the reliability of the evaluation indicators for the airflow field. Based on an analysis of the airflow field, improvements were proposed for the conventional cleaning device, with aerodynamic arc plates designed to be installed on the cleaning vibrating sieve. With these structural modifications in place, more field tests were performed to verify the cleaning effect. The proposed airflow guidance structure was found to be effective in improving the cleaning efficiency, as evidenced by the reduction in the impurity rate from 4.78% to 1.78% and the loss rate from 2.46% to 0.78%. The establishment of evaluation indicators for the airflow field, structural improvements made to the wind-sieve cleaning device, and the significant reduction in the impurity and loss rates associated with rice cleaning provide practical guidance for the design of cutting and longitudinal-flow combine harvesters.