小区小麦育种联合收获机无滞种脱粒装置脱输流场模拟及其低损伤特性研究

This program is based on the research of cropland plot combine harvesters with independent property rights. With longitudinal conical cylinder wheat seed threshing unit as its object of study, and the CFD, DEM, gas-solid two-phase flow coupling technique, distribution regularities of internal coupling flow field and the interactive relations of material particles during the working process as its approaches, this program aims to analyze the motion mechanism of the material particles in the threshing unit when the coupling airflow is in action. Ideally, no seed would be retained in the stripping shears, the threshing unit, and the cyclone separator. This program employs the limbic mechanical damage screening system to decect the internal damage of fusion techinique based wheat seeds，develops a damage recognition system of the threshing and delivering process, determines and ascertains the extent to which the threshing unit affects the biological characteristics of wheat seeds, thus mimimizes the damage. The researchers involved would select the staple wheat variety of Gan Su whose material properties are signicantly different to test, in order to obtain the structural and kinematic parameters that affect the operation performances of the threshing unit, then apply multi-objective genetic algorithms to optimize the parameters in order to improve the adaptability of the whole operation. Accordingly, this program ascertains axial delivering mechanism and seed damage mechanism during the threshing and delivering process as the coupling airflow takes effect. So as to fulfill the special demands of plot wheat breeding seed combine harvesters, that are high threshing rate, low damage rate, easy cleaning, and no intermixing .

项目依托具有自主知识产权的小区小麦育种联合收获机，以自主创新的纵轴流锥型滚筒小麦种子脱粒输送装置为研究对象，应用CFD法、DEM法、气固两相流耦合理论分析脱粒输送装置作业时内部耦合气流场的分布规律及物料颗粒流间的相互作用关系，意探求在耦合气流场作用下装置内部农业脱粒物料的运动规律，实现整机从割台到脱输装置直至旋风分离器全程无籽粒滞留；应用基于融合技术的育种籽粒内部机械损伤边缘检测方法，构建脱输损伤计算机识别系统，测定并探知该装置对其损伤籽粒生物学特性的影响，降低种子损伤；选取物料特性差异显著的甘肃主导育种小麦品种进行脱输试验，得出影响该装置作业性能的结构及运动参数，并基于多目标遗传算法进行工作参数优化，增强作业适应性。据此探明该装置在耦合气流场作用下确保装置内无籽粒残留的轴向输送机理及脱输过程中的种子损伤机理。以期实现小区小麦育种联合收获机高脱净、低损伤、无滞种、便清机、不混种的特殊要求。

小区小麦育种联合收获机具有高脱净、低损伤、无滞种、便清机的特殊要求，本项目研究以此为据，开展了对育种小麦穗头（籽粒、颖壳）的生物力学特性研究。借助试验法、有限元法及体式显微技术分别揭示了育种小麦籽粒在不同部位受载作用下的作用力分布及其脱粒损伤特性，探明育种小麦籽粒的含水率、放置方式、品种对其力学性质的影响机制。项目依托具有自主知识产权的小区小麦育种联合收获机，以自主创新的纵轴流锥型滚筒小麦种子脱粒输送装置为研究对象，基于CFD-DEM气固耦合理论对纵轴流锥型滚筒脱粒输送装置内部气固两相流的分布规律及物料颗粒流间的相互作用关系进行研究与阐明，解析了脱粒时间为0.001s~5s期间短纹杆-板齿式脱粒滚筒内物料运动模拟过程，并进一步明确了该纵轴流锥型滚筒脱粒输送装置作业过程中罩壳内出现籽粒滞留的影响因素，同时对制约该装置作业性能的结构、运动参数进行了优化与改进。基于离散单元法，建立脱粒混合物料离散元模型，数值模拟脱粒装置内混合物料的运动过程，通过构建3种不同脱粒元件模型（钉齿、短纹杆-板齿、组合齿），仿真模拟各类型滚筒作用下农业脱粒物料在装置内部的运动规律，对比分析出籽粒数量变化和受力情况，最终筛选出适宜于小区小麦收获作业的脱粒装置。将优化筛选的纵轴流锥型滚筒脱粒输送装置应用于创新研制的双层割台式小区小麦联合收获机上，探明了该装置在耦合气流场作用下可确保装置内无籽粒残留的轴向输送机理及脱输过程中的种子低损伤机理，同时验证了其作业性能和生产性能。