Abstract: In order to clarify the pneumatic conveying motion characteristics of the jujube in the pneumatic conveying device of the pneumatic suction jujube picker, the gas-solid two-phase flow in the pneumatic conveying device was simulated. Based on the gas-solid two-phase flow theory, a computational fluid model and a discrete element model were established, respectively. By computational fluid dynamics and discrete element method (CFD-EDM), the movement state, particle distribution and airflow field distribution of the inlet to the outlet of the device were simulated and analyzed, and the design of the cleaning box and the experimental verification were explored through simulation optimization experiments. The results showed that: ① most of the jujubes were discharged after hitting the grid and board, and a few jujubes remained in the box, and a small part was stuck or passed through the jujube grid. ② The separation chamber and the settlement chamber of the box  easily generated vortex phenomenon and increased energy loss. The average flow velocity through the grid was 17.85 m·s^-1 and the airflow trajectory was chaotic. ③After optimization, the airflow trajectory inside the box moved along the path of the box and reduces the occurrence of vortex phenomenon. The average flow velocity decreased to 6 m·s-1 to reduce the damage caused by the excessive kinetic energy of the jujube. ④The optimal structure of the corner diameter parameter of the box was 200 mm and the box inlet height was 65 mm. ⑤It was obtained through prototype test. Test results was closed to the simulation result. The above results showed that it was feasible to use the CFD-EDM two-phase flow coupling technology to simulate the pneumatic conveying device of the air-suction red date picker, and to optimize the box structure to shorten the conveying time of jujube in the pneumatic conveying device and improve the working efficiency of the prototype. The research results  provided reference for the simulation and optimization design of pneumatic conveying device of pneumatic jujube harvester.

Key words: agricultural machinery, air suction, jujube, CFD-EDM, simulation analysis

摘要： 为明确气吸式红枣捡拾机气力输送装置的运动特性，开展了气力输送装置气固两相流的模拟研究。基于气固两相流理论，分别建立了计算流体模型与离散元模型，通过计算流体力学与离散单元法(computational fluid dynamics-discrete element method)耦合求解，对红枣从气力输送装置入口到出口的运动状态、颗粒分布和气流场分布进行仿真分析，通过仿真优化试验探究清选箱箱体的设计并试验验证。结果表明：①多数枣撞击拦枣栅和挡枣板后被排出，少数残留于箱体中，少部分被拦枣栅卡住或通过拦枣栅；②箱体的分离室与沉降室易产生涡流现象，增大能量损失，通过拦枣栅的平均流速为17.85 m·s^-1，气流轨迹混乱；③优化后箱体内部气流轨迹沿箱体路径运动并减少涡流现象发生，通过拦枣栅的平均流速减小为6 m·s^-1，可降低红枣因自身动能过大而造成损伤；④优化后箱体的拐角内径为200 mm、箱体入口高度为65 mm时结构最佳；⑤样机试验结果与仿真试验结果较接近。上述结果说明，采用CFD-EDM两相流耦合技术对气吸式红枣捡拾机气力输送装置仿真是可行的，且通过优化箱体结构缩短红枣在气力输送装置中的输送时间、提高样机工作效率，该研究结果可为气力式红枣收获机气力输送装置仿真与优化设计提供参考。

关键词: 农业机械, 气吸式, 红枣, CFD-EDM, 仿真分析