地表坡度对油菜宽幅精量免耕播种机排种性能的影响

针对油菜种植区域作业方向的地表坡度变化影响气送式油菜宽幅精量免耕播种机排种性能的问题,该研究以播种机及气送式集排器为研究对象,构建了不同地表坡度下种子与外切圆弧型孔、种子-气流与集中分配器间的力学模型,建立了气送式集排器供种速率和排种速率的随机过程模型,应用EDEM仿真开展了作业方向的地表坡度、供种装置转速对供种装置供种速率影响的双因素试验,建立了地表坡度、供种装置转速对供种速率影响的数学模型;利用DEM-CFD耦合仿真分析了地表坡度对集中分配器排种性能的影响规律。仿真试验结果表明:以平整地表为基准,供种速率随地表坡度在-5°~5°内先增大而后逐渐减小;地表坡度绝对值为3°~5°时,供种速率的变化量达到50%;各行排种粒数一致性变异系数随地表坡度的增加而增大,变化区间为4.95%~14.91%。利用智能种植机械测试平台模拟播种机田间作业时不同地表坡度下的作业效果,结果表明,随着作业方向的地表坡度、前后往复摆动角度、前或后单向摆动角度的增大,各行排种量一致性变异系数均逐渐增大;仿真模型计算的各地表坡度下的供种速率与台架试验的平均误差为4.28%。根据试验结果建立播种机沿作业方向前后往复摆动的供种速率与地表坡度和供种装置转速、沿作业方向前或后单向摆动的供种速率与地表坡度和供种装置转速的数学模型,确定了不同地表坡度下,排种量与作业方向地表坡度和供种装置转速的匹配关系,以实现有坡度地表的排种量与平整地表的排种量趋同,为满足不同地表坡度下的播种作业提供参考。

Effects of land slope on seeding performance of a broad width precision no-tillage planter for rapeseed

Abstract: In view of the influence of the change of the land slope on the performance of the broad width precision no-tillage planter for rapeseed, the planter and the air-assisted centralized metering device were taken as the research objects, and the mechanical models between rapeseed and circumscribed arc type hole, rapeseed-air flow and central distributor were built under different land slope. The stochastic process model of the seed feeding rate and seeding rate of the air-assisted centralized metering device was established. The effects of land slope along the working direction and rotation speed of seed feeding device on seed feeding rate were analyzed by EDEM simulation and the corresponding mathematical model was established. EDEM-CFD coupling simulation was used to analyze the influence of the land slope along the working direction on the seeding performance of the central distributor. The simulation results showed that the seed feeding decreased gradually with increase of the land slope angle in the range of -5°-5°. The variation of seed feeding rate could be up to 50% compared with no tilt when the absolute value of land slope angle was in the range of 3°-5°. The uniformity variation coefficient of seed quantity of each seed outlet increased with the increase of land slope angle, and the uniformity variation coefficient ranged from 4.95% to 14.91%. The land slope had a significant effect on the seed feeding rate and the uniformity variation coefficient of seed quantity of each seed outlet. The intelligent test platform of planting machines was used to simulate the field working effect of planter under the different land slope. The experiment results indicated that with the increase of absolute value of land slope angle along with the working direction, the angle range of the planter swing front and back, the angle range of the planter swing front or back in one way and the uniformity variation coefficient of the seed quantity of each seed outlet all increased gradually. With the increase of the absolute value of the land slope angle, the operations of continuous uphill or downhill had little effects on the variation coefficient of seed feeding rate stability. the uniformity variation coefficient of seed quantity of each seed outlet increased gradually, and the uniformity variation coefficient of it''s ranged from 4.76% to 13.85%. With the increase of the angle range of front and back reciprocating swing, the seed feeding rate had obvious changes, the uniformity variation coefficient of seed quantity of each seed outlet increased gradually, and the uniformity variation coefficient of seed quantity of each seed outlet ranged from 4.76% to 10.27%. The effect of front or back single swing on seeding performance showed with the increase of the angle range of front or back swing in one way, the variation coefficient of seed feeding rate was slightly higher than that of with no tilt, the uniformity variation coefficient of seed quantity of each seed outlet increased gradually, and the uniformity variation coefficient of seed quantity of each seed outlet ranged from 6.76% to10.71%. The average error of seed feeding rate between the theoretical calculated by the simulation model and the bench test was 4.28%. The matching relationship between the seeding quantity, the land slope angle along the working direction and the rotation speed of seed feeding device can ensure the planter has the same seeding quantity when the planter working on the land with slope similar to that on the flat land, which can provide a reference for the structure optimization of the planter and the air-assisted centralized metering device to meet the seeding operation under different land slopes.