玉米收获机清选筛体结构优化

Structure Optimization of Cleaning Screen for Maize Harvester

为提高玉米籽粒收获机风筛式清选装置的清选效果,通过对比编织筛和贝壳筛的筛分性能,以贝壳筛筛体结构为主要研究对象,采用CFD-DEM耦合的方法,选取振动筛筛分效率和籽粒清洁率为性能指标,筛孔长度、筛孔高度和筛孔纵向间距为试验因素,设计二次正交旋转组合试验。通过响应曲面方法对试验结果分析,并利用DesignExpert软件对回归数学模型进行多目标优化。结果表明,各因素对试验指标影响由强到弱顺序为:筛孔高度、筛孔纵向间距、筛孔长度。筛体结构参数优化为:筛孔长度21.68 mm,筛孔高度10.86 mm,筛孔纵向间距55.04 mm。通过试验验证此因素条件下振动筛筛分效率由81.79%提高到89.91%,籽粒清洁率增加到97.28%,清选装置的性能得到提高。

In order to improve cleaning performance of cross air-and-screen cleaning device in maize harvester, through comparing the screening performance of woven screen and shell screen, the structure of shell screen was selected as the main object of study. In order to obtain the optimal parameters of the shell screen, computational fluid dynamics and discrete element method （CFD- DEM） were coupled in the quadratic orthogonal rotational-combinational simulation tests. Objective indexes were screening efficiency of shell screen and cleaning rate of grain. The factors were the length and height of screen hole and the space between screen holes. The test data were analyzed by the response surface method and the regression mathematical models were multi-objective optimized by using Design - Expert software. Simulation results showed that height of screen holes had the most significant effect on the indexes, followed by the space between screen holes, then the length of screen holes. The optimized parameters were the length of screen hole of 21.68 mm, height of screen hole of 10.86 mm and space between screen holes of 55.04 mm. The results of verified test showed that screening efficiency was increased from 81.79% to 89.91% and the cleaning rate of grain was increased to 97.28% , which were consistent with the simulated results. The performance of the cleaning device was enhanced.