基于离散元法的杂交稻振动匀种装置参数优化与试验

    Parameter optimization and experiment of vibration seed-uniforming device for hybrid rice based on discrete element method

    • 摘要: 杂交稻栽培要求少本稀植、利用分蘖能力提高产量,现有的机械化播种技术不能满足此要求,亟需进行杂交稻精密播种技术的机理探讨。为探明振动匀种装置匀种过程中V-T型振盘的振频和振幅对杂交稻种群运动规律的影响,以及种群流动特性对播种性能的影响,该文基于离散元法,采用Hertz-Mindlin无滑动接触模型,实现了V-T型振盘工作过程模拟,得到振盘振频为57~59 Hz时,种群在振盘中分布均匀,播种效果较好。试验验证表明,利用离散元法模拟振动匀种装置匀种过程具有较高的准确性。在仿真结果的基础上,选取振盘振动臂材料、振动器安装角、气动振动器进气压强作为试验因素,进行了振动匀种装置参数优化试验,获得了杂交稻种子低播量下的最佳工作参数组合为振盘振动臂材料为60Si2Mn,振动器安装角度为47.5°,进气压强为0.26 MPa;此时播种合格指数为92.86%,空穴指数为1.14%,有效地提高了现有播种装置的性能。该研究对提高杂交稻精密播种技术提供了参考。

       

      Abstract: Hybrid rice requires sparse and precision seeding, and it increases yield by its strong tillering ability. But the existing mechanization planting technology can not meet the planting requirement of hybrid rice, and it is necessary to understand the mechanism of hybrid rice precision seeding technology. This paper studied the vibration seed-uniforming device in the seedling devices of hybrid rice through the theoretical analysis, simulations and experimental setup, in order to clarify the influence of the vibration frequency and amplitude of its V-T type vibration plate on the movement of seeds and the influence of seed flow characteristics on seeding performance in the sowing process, which could lead to an improvement in the seedling performance. Firstly, through the kinetic analysis of individual seed, the seed gliding and jumping conditions on the V-T type vibration plate were obtained, and the amplitude, frequency, and vibrator installation angle of the vibration plate were identified as the 3 key factors that affected the sowing performance. Secondly, to further study the movement principles of seeds on the vibration plate, the working process of the V-T type vibrating plate was simulated using the discrete element method(DEM) analysis software EDEM and the Hertz-Mindlin non-slip model. In the EDEM software, seed particles were modeled as spheres with 10 different diameters, in order to more accurately depict the characteristics of actual hybrid rice seeds. When designing the simulation motion parameters of the V-T type vibrating plate, since the pneumatic vibrator was installed on the center of the V-T type vibration plate, which led to varied vibration parameters across the plate, the vibration frequency and amplitude at different parts of the vibration plate were measured separately and adopted in the model. Next, 8 groups of simulation experiments were designed by varying the amplitude and frequency of the vibration plate, and the successful sowing rate was used as the standard to evaluate sowing performance. The simulation result showed that vibration frequency from 57 to 59 Hz led to the uniform distribution of seeds on the V-T type vibration plate and relatively better sowing performance. To validate the feasibility and accuracy of the simulation result, a single-factor experimental design was implemented. The result indicated a high accuracy for the EDEM simulation of the sowing process using the vibration seed-uniforming device, and a relative error of from 1.15% to 6.19% in the successful sowing rate was shown between the simulation and experimental value. Finally, based on simulation and experimental results, 3 experimental factors, the material choice of the vibration arms, the installation angle of the vibrator and the pneumatic vibrator inlet pressure, were chosen to carry out parameter optimization experiments of vibration seed-uniforming device. The optimal parameter combination was obtained, which was 60Si2Mn as the material of vibration arms, 47.5° as installed angle of vibrator, and 0.26 MPa as the pneumatic vibrator inlet pressure. With this optimal parameter combination, the performance of the vibration seed-uniforming device was improved, and the successful sowing rate was 92.86% and the cavity rate was 1.14%. This study provides a basis for the future research on the improvement of the precision sowing technology of hybrid rice.

       

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