Authors

Abstract

To improve the quality of air suction jujube picker, the CFD-DEM coupled method is used to numerically simulate the conveying process of jujube particles and explore the motion state, particle collision and energy loss of jujube particles in the pipeline. The erosion rate is selected as an evaluation index to discuss the influence of wind velocity, bending angle and diameter on the conveying process. The simulation results show that the collisions between jujubes, as well as the collisions between jujubes and pipe wall have an impact on the conveying performance, and the latter is more significant. The erosion rate is positively correlated with the wind velocity, negatively correlated with the pipe diameter, and the bending angle first decreases and then increases. The influence degree of factors on the erosion rate is: wind velocity > bending angle > pipeline diameter. The optimal parameter combination is a wind velocity of 28 m•s-1, a bending angle of 105 °, and a pipe diameter of 130 mm. At this time, the value of erosion rate is the lowest and the number of collisions and energy loss between jujube particles are reduced by 37.3 % and 13.87 % year-on-year, and those between jujube particles and pipe wall are reduced by 17.45 % and 17.61 % year-on-year, respectively. The test results show that the conveying pipe with optimized structural parameters can reduce the jujube skin damage rate by 2.06 %. The results of this study can provide a reference for the design and optimization of the air suction jujube picker.

Abstract in Chinese

中小型气吸式红枣捡拾机利用负压吸送原理完成红枣果实的输送作业，但因红枣与红枣、红枣与管壁碰撞等问题造成红枣表皮轻微损伤，为提高气吸式红枣捡拾机作业质量，利用CFD-DEM耦合的方法对输送管输送红枣颗粒过程进行数值模拟，探究红枣颗粒在管路内的运动状态、颗粒碰撞及能量损失情况，并以侵蚀速率为评价指标讨论风速、弯管角度和直径对输送过程的影响。仿真结果表明，红枣与红枣、红枣与管壁两种碰撞均对输送性能有影响，且后者更为显著；侵蚀速率与风速呈正相关，与管路直径呈负相关，与弯管角度则呈现先减小后增大；各因素对侵蚀速率的影响程度为风速>弯管角度>管路直径，最优参数组合为风速28m•s-1，弯管角度105°，管路直径130mm，此时侵蚀速率值最低且枣间颗粒碰撞次数和能量损失同比降低37.3%和13.87%，红枣颗粒与管壁碰撞次数和能量损失同比降低17.45%和17.61%。验证试验结果表明，结构参数优化后的输送管对红枣表皮损伤率降低2.06%。该研究结果可为气吸式红枣捡拾机的设计与优化提供参考。