基于离散元法的谷子脱粒机理与多品种脱粒参数测试

Threshing Mechanism and Multi-variety Threshing Parameter Testing of Foxtail Millet Based on Discrete Element Method

摘要:

针对谷子籽粒细小、穗部结构复杂所导致的脱净率低、籽粒损伤大、功耗高等问题,本文提出一种基于骆驼口腔角质化乳突挤搓机理的低损脱粒方法,设计多乳突阵列仿生脱粒元件,搭建纵轴流谷子脱粒试验装置。建立了谷穗与仿生元件碰撞接触力学模型和基于离散元法的柔性谷穗模型,并仿真模拟了不同齿型脱粒过程。探究了脱粒元件、滚筒转速和脱粒间隙对不同品种谷穗脱净率、破碎率、损失率及单穗脱粒功耗的影响规律。结果表明,脱粒元件对脱粒性能影响显著,滚筒转速主要影响破碎率和单穗脱粒功耗,脱粒间隙对响应面各指标均有显著影响,交互作用对破碎率影响显著。最佳组合为仿生元件、滚筒转速701.512 r/min、脱粒间隙6.081 mm,此时脱净率、破碎率、损失率和单穗脱粒功耗分别为96.397%、0.767%、1.629%和69.649 W。构建的响应面回归预测模型对多品种脱净率、破碎率、损失率预测相对误差不超过1.58%、7.82%、2.82%,单穗脱粒功耗相对误差不超过10.67%,对脱粒质量具有较好的预测精度。研究结果为谷子低损脱粒装置设计与多品种脱粒参数优化提供参考。

Abstract:

Aiming to address the problems of low threshing completeness, high grain damage, and high power consumption caused by the small grain size and complex panicle structure of foxtail millet, a low-damage threshing method based on the rubbing and kneading mechanism of keratinized papillae in the camel oral cavity was proposed. A bionic threshing element with a multi-papilla array was designed, and a longitudinal axial-flow foxtail millet threshing test device was developed. Based on Hertzian contact theory a collision contact mechanics model between foxtail millet panicles and the bionic threshing element was established, and a flexible foxtail millet panicle model based on the discrete element method was constructed. Mechanical calibration and validation were carried out, and comparative simulations of the threshing processes with different tooth types were conducted. Jingu 21, Zhangza 16, and Tonggu 58 were used as test materials to investigate the effects of threshing element type, cylinder rotational speed, and threshing clearance on threshing completeness rate, grain breakage rate, grain loss rate, and power consumption per panicle, so as to determine the optimal tooth type and parameter combination. The results showed that the threshing element type had a significant effect on threshing performance, cylinder rotational speed mainly affected grain breakage rate and power consumption per panicle, and threshing clearance had significant effects on all-response variables. The interaction between cylinder rotational speed and threshing clearance had a significant effect on grain breakage rate. The optimal tooth type was determined to be the bionic tooth type. When the cylinder rotational speed was 701.512 r/min and the threshing clearance was 6.081 mm, the threshing completeness rate, grain breakage rate, grain loss rate, and power consumption per panicle were 96.397%, 0.767%, 1.629%, and 69.649 W, respectively. The relative errors of threshing completeness rate, grain breakage rate, and grain loss rate for different varieties did not exceed 1.58%, 7.82%, and 2.82%, respectively, and the relative error of power consumption per panicle did not exceed 10.67%. The model showed good prediction accuracy for threshing quality indicators. The research result can provide a reference for the design of low-damage foxtail millet threshing devices and the optimization of threshing parameters for different varieties.