残膜在振动风筛式分离装置气固两相流场中运动规律分析

At present, farmland soil within the residual film has seriously affected the yield of crops and agricultural sustainable development research group, after nearly ten years of research, developed a series of removal of topsoil in plastic film machine, by lack of residual plastic film, soil and crop residue in the separation device of the gas solid two phase flow system, product performance and structure stable, not large area promotion and application of. The project in the early development of air - vibrating screen type soil and residual membrane separation device as the research object, the soil remnant film mixture material physical and mechanical property on the basis of the study, establish soil, residual film on the airflow field and the screen surface under the action of the equations of motion; study of soil, residual interactions between the membrane, based on the discrete particle block group model, the analysis of particle blocks on the screen surface layer, migration and screening rules, and perform numerical simulation. Finally, using high speed camera system acquisition single film and group vibrating screen separation process sequences of images, the use of image processing technology to carry on the analysis, extraction of single piece of film movement, verify the correctness of theory analysis, to determine the separation device of fan airflow direction and magnitude, vibrating screen amplitude, frequency, direction angle and the sieve of the shape and size, optimization of device structure and motion parameters, to design efficient soil remnant film mixture separation device the theory basis.

目前，农田耕层内残膜已严重影响作物的产量和农业可持续发展，课题组经过近十年的研究，研制了系列清除耕层内残膜的机具，因缺乏对残膜、土壤及残茬在分离装置气固两相流场的系统研究，产品性能和结构不稳定，无法大面积推广应用。本项目以前期研制的气流-振动筛式土壤与残膜分离装置为研究对象，对土壤残膜混合体物料的物理机械特性研究的基础上，建立土壤、残膜在气流场和筛面作用下的运动方程；研究土壤、残膜之间的相互作用，构建基于离散的粒块群模型，分析粒块群在筛面上的分层、迁移和透筛的规律，并进行数值模拟。最后运用高速摄像系统采集单块残膜和群的振动筛分离过程序列图像，利用图像处理技术进行分析，提取单块残膜的运动规律，验证理论分析的正确性，从而确定分离装置中风机的气流方向与大小，振动筛的振幅、频率、方向角及筛孔的形状与大小等，优化装置的结构及运动参数，为设计高效土壤残膜混合物料的分离装置提理论依据。

项目设计制作了风-筛式土壤残膜分离装置，运用Pro/E软件对结构装置进行运动仿真，以土壤残膜筛分率为研究目标，利用风筛式土壤残膜分离装置试验平台，使用CDF专业软件FLUENT，对气流场进行仿真计算，并对筛面气流速度进行布点测量，找出筛面气流场的分布规律；分析了风机安装及参数对气流场分布的影响作用，结合气流场研究土膜最佳抛起状态时振动筛的参数，研究了气固流场对筛分效果的影响，优选了风机、安装参数等。通过分析、仿真与试验确定了筛体运动指标 ，振动筛纵向和横向位移；风选室内风速沿筛面长度方向呈两头低中间高，沿筛面宽度方向整体呈现两边高中间低，在离心风机安装倾角为5 °，出风口风速20 m/s，曲柄转速180 r/min，筛面倾角6 °和鱼鳞筛开度20 °时，残膜回收率最高达93.2%。证明风-筛式土壤残膜分离装置在分离土壤中的残膜有效可行，为设计高效土壤残膜混合物料的分离装置提理论依据，对农田残膜污染治理提供新型、性能可靠的农业机械，推动农业机械进程，推动农业可持续发展有重要的意义。