离心侧抛式藕田撒肥器设计与试验

针对藕田机械化施肥实际需求,该研究设计了一种离心侧抛式撒肥器。通过建立单个肥料颗粒在叶片上受力的理论模型,确定影响颗粒运动特性的主要参数为撒肥盘转速、叶片倾角和叶片偏角。以肥料喂入速率以及上述因素为影响因素,利用EDEM软件进行单因素仿真试验,结果显示以撒肥器中心为原点,沿抛撒方向,肥料在单个统计区域的分布量变化趋势为先升高后降低。定义肥料分布最多的单个统计区域与撒肥器间的距离为峰值距离,以肥料分布均匀性变异系数和峰值距离为评价指标进行正交旋转仿真试验,根据试验结果利用Design-Expert软件对撒肥器结构进行优化,求取峰值距离为10、21m且均匀性变异系数最小的两种叶片各自对应的叶片倾角和叶片偏角分别为8.5°、17.5°和11.5°、–1.9°。以上述结构撒肥器开展仿真与实际撒肥试验。仿真结果显示:撒肥盘转速1 250 r/min、喂入速率0.316 kg/s时,肥料分布均匀性变异系数、峰值距离、作业幅宽分别为19.43%、21 m和29 m,实际试验结果分别为21.95%、18.6 m和24.5m。以藕田追肥中常用肥料尿素、复合肥、磷肥为对象开展撒肥性能试验,结果显示,撒肥盘转速、喂入速率、肥料种类、肥料种类与转速的交互项、肥料种类与喂入速率的交互项对肥料分布均匀性变异系数影响极显著(P0.01),转速、喂入速率、种类对作业幅宽影响极显著(P0.01)。该研究结果可为藕田撒肥机械设计提供重要参考。

Design and experiments of the centrifugal side throwing fertilizer spreader for lotus root fields

Mechanizedfertilization has widely been one of the most important steps for the highyield of crops.In this study,a centrifugal side throwing fertilizer spreader was designedforthe lotus root field. Firstly, atheoretical model was established for the force of a single fertilizer particle on the blade. The main parameters were then determined for the particle motion,such as the rotating speed of the fertilizer tray, theblade inclination angle, and the blade deflection angle. Secondly, EDEM discrete element simulation software was utilizedto optimize the performance of the spreader.A single factor test was carried out, where the fertilizer feed rate and the above factors were taken as the influencing factors. The results showed thatthe weightdistributionof fertilizer increasedfirst and then decreasedin a single statistical area when taking the center of the spreader as the originalong the throwing direction. Specifically, the quality of fertilizer with the most distribution in a single statistical region was called the peak value, and the distance between this region and the fertilizer spreader was called the peak distance, to accurately quantify the distribution index of fertilizer. The rotating speed of the fertilizer tray and the blade inclination angle poseda significant impact on the peak value and peak distance of fertilizer distribution, whereas, the blade deflection angle and feed rate onthe peak value.An orthogonal rotation simulation test was carried out with the uniformity variation coefficient and peak distance as the evaluation indexes.It was found that there was an extremely significant influence on the uniformity variation coefficient (P<0.01), including the rotating speed of fertilizer tray,the blade inclination angle, the blade deflection angle,the interaction between them,the interaction term between the inclination angle of blade and feed rate,as well asthe quadratic term of blade inclination angle.There was an extremely significant effect on the peak distance (P<0.01), including the rotating speed of fertilizer tray, the blade inclination angle, and the quadratic term, the quadratic term of feed rate.Design-Expert software was utilized to optimizethe structure of the spreader.The blade structure parameters were then calculated to minimize the uniformity variation coefficient, when the peak distance was 10 and 21 m, the blade inclination, and deflection angle were 8.5°, 17.5°, 11.5°, and -1.9°, respectively.Subsequently, the simulation and actual fertilizer application were carried out to evaluate the performance of the fertilizer spreader with the optimalstructural parameters.The simulation results show that the uniformity variation coefficient, peak distance, and working width were 19.43%, 21m, and 29m, respectively,when the rotating speed of the fertilizer tray was 1 250 r/min, and the feed rate was 0.316 kg/s. By contrast, the specific parameters in an actual contrast testwere 21.95%, 18.6m, and 24.5 m, respectively, wherethe errors with the simulation were 12.95%, 11.42%, and 15.51%, respectively. A performance test of fertilizer spreader was carried out with large particle urea, compound fertilizer, and phosphorus fertilizer commonly used in lotus root field topdressing. The results showed that the operation effect of large particle urea was better at 1 300 r/min, feed rate of 0.15kg/s, and operation width of 24m. At this time, the uniformity variation coefficient was 24.56%. The analysis of variance showed that the rotating speed of fertilizer tray,feed rate, fertilizer type, and the interaction term between fertilizer type and feed ratepresentedan extremely significant impact on the coefficient of variation (P<0.01). The rotating speed of fertilizer tray, feed rate,and type presentedan extremely significant impact on the operation width (P<0.01).The finding can provide an important reference for the design of fertilizer spreading machinery in the lotus root field.