摘要
针对现有气吸式排种器充种环节工作压力要求高、高速作业时充种性能不佳,导致排种质量下降的问题,采用主动驱导种群、减少局部种间接触的方法,提高排种器高速条件下的充种率,并基于此设计了一种驱导辅助充种气吸式精量排种器。分析了排种器充种过程中种子的受力状态,阐述了排种盘导种槽辅助充种的工作原理,以及在充种过程各阶段提高种子充填率的设计思路;对导种槽外形曲线方程、斜面倾角进行了理论计算,确定了曲线的基本参数;利用气固耦合数值分析方法 CFD-DEM,以型孔处局部空隙率为指标,进行了单因素仿真试验,确定了导种槽曲线方程的基圆半径最优值。为了验证设计结果,在工作压力-5、-6 kPa条件下,分别与其他2种气吸式排种器进行速度单因素对比试验,试验结果表明,所设计的排种器在高速条件下的漏充率优于其他排种器。对所设计的排种器进行了前进速度、工作压力的双因素试验,通过多目标优化方法,确定了排种器的最佳工作参数。将所设计的排种器安装在气力式玉米免耕播种机上,在3个工作速度下进行了单因素田间试验,结果表明,当作业速度为9. 11 km/h时,粒距合格指数为95. 48%,高速条件下充种性能较为稳定。
Aiming to solve the problem of poor seeding quality of the current air-suction vertical disc precision seed metering device caused by higher demands for working pressure during seed-filling process at high speed working conditions. One kind of air suction precision seed metering device with guided assistant seed filling plate was designed to improve the singulation index( SI) of the seed meter at high speed. Basic parameters of the curve were expounded,the source of resistance during the seed-filling was analyzed,and the ideal filling state of the various segments of the seed was presented. An optimal value of the base circle radius of the disturbance groove curve equation was proposed by the calculation of disturbance trough curve equation,the calculation of edge tilt angle,and a single factor simulation experiment was carried out with the CFD-DEM method by gas-solid coupling numerical analysis with local void ratio as an indicator. In order to verify the design results,an single factor simulation experiment which compared with two domestic popular air-suction vertical disc precision seed metering devices was carried out under the working wind pressure of-5. 0 kPa and-6. 0 k Pa. The results showed that the missing rate and the qualified rate were better than those of the other two seed metering devices. Twofactor experiments of operation pressure and forward speed were made on the designed seed metering devices,the optimal operating parameters were proposed by multi-objective optimization analysis. The developed seed metering device was installed on the electrical drive air suction type seeding machine,and the single factor repeating factor test was carried out at three working speeds. When the working speed was 9. 11 km/h,the grain distance qualified index was 95. 48%,and the seed-filling had a better performance at high speed conditions.
引文
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