Optimization of airflow nozzle structure for vegetable soybean sorting equipment based on CFD

Aiming at problems of poor blowing efficiency and high air consumption in airflow nozzle used for vegetable soybean sorting, a conical airflow nozzle was selected as research object．Based on CFD software, key structural parameters such as outlet diameter, contraction length, and contraction angle were optimized and analyzed．Results indicated that outlet diameter exerted the most significant impact on axial average velocity, far greater than contraction angle, while contraction length had the least influence．Air consumption was mainly affected by outlet diameter, with relatively minor effects from contraction angle and contraction length．To maintain airflow velocity performance while effectively reducing air consumption, optimalstructural parameters combination was determined as: outlet diameter of 2 mm, contraction length of 2 mm, and contraction angle of 10°．Sorting validation tests showed that at 0.6 MPa pressure and a conveyor belt speed of 1 m/s, optimized airflow nozzle achieved a sorting efficiency of 96.64%, 11.43 percentage points higher than cylindrical nozzle．A theoretical basis for designing conical airflow nozzles in field of agricultural product sorting was provided．