油菜联合收获田间落粒气力式收集方法研究

The high loss rate is a bottleneck problem of the current rape combine harvester in our country. The higher the maturity is and the lower the moisture content is, the greater the cutting platform or field shattering loss is in the front part of the machine, and the smaller the loss of the threshing, separating and cleaning in the behind; and vice versa. Not enough maturity causes low oil rate, while high moisture content will increase difficult of the threshing, separating and cleaning. Therefore consideration should be given to both the front and behind loss of the equipment. While the threshing, separating and cleaning devices are optimized, at the same time new types of the cutting platform should be developed to fit a new harvest time which is shifted to backwards appropriately or on a sunny afternoon for a higher maturity and a lower moisture content. This application will study the pneumatic collection method and devices for the splashing loss according to the features of mature rape and the existing traditional harvester cutting platform as follows: to research the gas-solid coupling mechanism between the material mixture and the airflow; to reveal the negative pressure airflow field distribution law with obstacles out of the collection channel; to set up the collision physical model between grain and grain or grain and obstacles; to calculate the trajectory of grain, and obtain the effective collection area of the monomer under a given negative pressure; to clarify the gas-solid flow pattern in the internal collection channel, design and optimize the channel structure, size, location of entrance and airflow parameters; to investigate the occurring mechanism of the entrance blockage,and to seek anti-blocking and blockage removing strategy. This study may lay a theoretical and technical foundation for the development of new rape combine harvester of high quality and efficient energy.

过高的损失率是制约当前我国油菜联合收获机械发展的瓶颈。成熟度越高含水率越低时，前方割台/田间落粒损失越大，后续脱粒分离和清选损失越小；而成熟度不够会导致出油率下降，含水量偏高会导致脱分和清选困难。因此应统筹考虑机具的前后损失，优化脱分及清选装置的同时,开发与收获时机适当后移或为晴天午后相适应的新型割台。本申请围绕成熟期油菜的机械适收特性,开展与现有联收机割台配套的田间落粒气力式收集方法及装置的研究。具体研究气流与物料混合物间的气固耦合机理，揭示收集装置通道外部多障碍物负压气流场的分布规律，建立籽粒与籽粒及籽粒与障碍物之间的碰撞物理模型，计算籽粒运移轨迹，获得收集单体在给定负压值下的有效收集范围；阐明通道内部气固两相流动规律，设计并优化其结构、尺寸、入口分布位置及气流参数；研究入口堵塞发生机理，寻求入口抗堵排堵策略。本研究将为开发优质高效节能的新型油菜联合收获机具奠定一定的理论和技术基础。

割台损失在当前我国油菜联合收获过程的总损失中占主导地位。本项目旨在探索在油菜联合收割机行进过程中利用气流方式在线收集割台前方下落油菜籽粒的方法和装置，以减小割台损失和收获总损失。项目利用数值模拟和台架试验两种手段系统研究了基于2种原理（负压气流、正压气流）3种形式（横向负压气流、纵向正压气流、横向正压气流）的气力收集方法、装置及其产生的气流场对下落油菜籽粒的运移过程及规律。研究结果表明，负压气流在非受限空间范围（非管道、壁面等受限空间内）中的作用效果（气流参数的持续性及对内部物体如油菜籽粒的运移作用）不够明显，而正压气流则具有相对明显作用效果；横向正压气流收集方式较纵向正压气流收集方式对于割台前方下落油菜籽粒具有更好的收集效果。此外还通过高速摄影方式精确测量了油菜籽粒在点面碰撞过程中的恢复系数。研究为进一步设计合理的油菜割台前方下落籽粒收集装置建立了理论基础。