茶园离心撒肥装置工作参数优化与试验研究

发布时间：2018-05-01 20:12

本文选题：茶园 + 撒肥装置　；参考：《江苏大学》2016年硕士论文

【摘要】：目前茶园中尚无专用的施肥装备,而传统的大田撒肥装置不适于在窄行距的茶园中作业;茶园中常用的施肥方式主要依靠人力,劳动效率低、强度高。因此,研制一种茶园专用的高效施肥装置,具有重要的实际意义。本论文在农业部公益性行业(农业)科研专项“茶园综合作业机械化技术与装备研究”项目资助下,基于离心撒肥装置的工作过程及其结构分析,在测定肥料颗粒力学参数及分析其运动的基础上,对撒肥过程进行仿真;然后通过台架试验研究优化撒肥工作参数,并进行了田间验证。主要研究内容与结果如下:(1)茶树专用肥料颗粒力学参数测定为了建立准确真实的肥料颗粒模型,以茶园中茶树需求量最大的专用肥料尿素和复合肥为研究对象,分别对其的碰撞恢复系数、三轴尺寸、密度、刚度系数、摩擦系数等参数进行了测量。测量结果为:尿素颗粒与复合肥的碰撞恢复系数分别为0.39和0.41;尿素和复合肥的平均长度分别为3.80 mm和3.42 mm,平均宽度分别为3.57 mm和3.21 mm,厚度的均值分别为3.59 mm和3.19 mm,等效直径的均值分别为3.64 mm和3.27 mm,两种肥料颗粒球形度均大于93%;尿素和复合肥的颗粒密度分别为颗粒密度为1.61g/cm3和1.10 g/cm3,堆积密度分别为0.75 g/cm3和0.90 g/cm3;肥料颗粒的刚度系数分别为132.88 N/mm和85.51 N/mm;两者的静摩擦系数为0.59和0.55,动摩擦系数为0.54和0.41;含水率分别为0.37%和1.10%。(2)撒肥装置总体设计与肥料颗粒运动分析对茶园撒肥装置的结构进行总体设计,其中主要包括机架、肥料箱、仿蹄形下料口和叶片位置倾角可调的偏置式离心盘等部件,同时建立了肥料颗粒在离心盘上和脱离离心盘后的两种动力学模型,并分析了茶园撒肥的工作过程。其中,仿蹄形下料口既能缓冲肥料颗粒流的速度,又可以避免肥料颗粒的过多的集中于离心盘的中心;离心盘活动叶片既方便调整来改变撒肥宽幅,又能够提高撒肥的均匀性;机架的结构与尺寸根据手扶拖拉机前端结构尺寸确定,将撒肥装置固定于手扶拖拉机的前端,在撒肥的同时可使手扶拖拉机后置的旋耕机将所撒肥料覆于土中。(3)离心撒肥过程仿真根据肥料颗粒的力学参数,建立肥料颗粒的球形模型和撒肥装置的几何模型,并确定肥料颗粒的接触模型和最优时间步长;为满足0.8 m的合适撒肥宽幅,经试验测试知,与之对应的离心盘转速约为300 rpm;通过EDEM仿真茶园撒肥装置的撒肥过程,初步分析了撒肥装置行走速度、离心盘叶片个数、叶片偏置角度等单一因素对颗粒分布变异系数的影响,同时对肥料颗粒的群体分布、单颗粒速度变化、受力变化情况和位移变化情况进行分析。仿真结果表明:当行走速度为0.6 m/s、偏置角度为30°和叶片个数为4片时,变异系数较小,均具有较好的撒肥效果;由肥料颗粒群体分布情况分析可知,撒肥过程中肥料颗粒分布的纵向均匀性较好,横向均匀性较差;通过肥料颗粒速度、受力及位移变化分析可知,肥料颗粒在通过仿蹄形下料口时,速度急剧减小,受力变大,位移变化缓慢,说明撒肥装置的下料口起到了缓冲肥料颗粒流速的作用,避免了高速肥料颗粒流对离心盘的冲击。(4)撒肥效果试验及工作参数优化由仿真分析可知,当行走速度为0.6 m/s、偏置角度为30°和叶片个数为4片时,变异系数均较小,但为探究这三个因素的交互作用对撒肥均匀性的影响以及最优的工作参数,采用三因素三水平的二次回归正交旋转中心组合设计试验方法进行台架试验;根据试验数据分析的结果,建立起叶片个数、偏置角度和行走速度关于分布变异系数的回归模型;在各因素范围的约束条件下,对目标函数进行优化;并利用田间试验对台架试验的最优结果进行了检验。优化结果为:叶片个数为5、偏置角度为15.72o、行走速度为0.61 m/s,此时分布变异系数达到最小值,为10.30%。田间验证试验表明:在最优作参数下,茶园撒肥装置的撒肥均匀性较好,实测值与理论预测值的平均相对误差为10.15%,最大相对误差为22.14%。与未优化的撒肥装置相比,优化后的工作参数对撒肥的均匀性有了显著提升。本论文设计并研制了一种茶园专用撒肥装置,并优化了其工作参数;台架与田间试验表明,该离心撒肥装置在优化的工作参数下,撒肥均匀性较好,可用于茶园施肥。
[Abstract]:There is no special fertilizer equipment in the tea garden at present, but the traditional field dressing device is not suitable to work in the narrow distance tea garden. The common method of fertilization in the tea garden is mainly dependent on manpower, low labor efficiency and high intensity. Therefore, it is of great practical significance to develop a kind of high efficiency fertilization device for tea garden. This paper is in the public welfare of the Ministry of agriculture. Under the support of the project of "mechanization technology and equipment research of Tea Garden comprehensive operation", based on the analysis of the working process and structure of the centrifugal fertilizer plant, the process is simulated on the basis of determining the mechanical parameters of the fertilizer particles and analyzing the movement of the fertilizer. The main contents and results are as follows: (1) the determination of the mechanical parameters of the special fertilizer for tea tree in order to establish an accurate and true fertilizer particle model, the research object of the special fertilizer urea and compound fertilizer, which have the largest demand for tea trees in the tea garden, and the coefficient of the collision recovery, the size of the three axis, the density and the stiffness system respectively. The results are as follows: the impact recovery coefficient of urea and compound fertilizer is 0.39 and 0.41, respectively, the average length of urea and compound fertilizer is 3.80 mm and 3.42 mm respectively, the average width is 3.57 mm and 3.21 mm respectively, the mean thickness is 3.59 mm and 3.19 mm respectively, the mean diameter of the equivalent is 3.64, respectively. The sphericity of two kinds of fertilizer particles in mm and 3.27 mm is more than 93%. The particle density of urea and compound fertilizer is 1.61g/cm3 and 1.10 g/cm3, respectively, the density is 0.75 g/cm3 and 0.90 g/cm3, respectively. The stiffness coefficient of fertilizer particles is 132.88 N/mm and 85.51 N/mm, respectively, and the static friction coefficient is 0.59 and 0.55, and the dynamic friction coefficient is 0.5. 4 and 0.41, the overall design of the fertilizer plant and the particle motion analysis of the 1.10%. (2) fertilizer, respectively, are designed for the structure of the tea garden fertilizer plant, including the frame, the fertilizer box, the imitating hoof shape and the offset centrifugal disc with adjustable angle of the blade position, and the fertilizer particles are established on the centrifuge disk. The two dynamic models were separated from the centrifuge disc, and the working process of the tea plantation was analyzed. Among them, the imitating hoof shaped cutting mouth can not only buffer the velocity of the fertilizer particle flow, but also avoid the excessive concentration of the fertilizer particles in the center of the centrifuge disk; the active blade of the centrifugal disc can be easily adjusted to change the width of the fertilizer and increase the fertilizer. The structure and size of the frame are determined according to the size of the front structure of the walking tractor, and the fertilizer device is fixed to the front end of the walking tractor, and the fertilizer can be covered with the soil. (3) the process of centrifugation is used to simulate the mechanical parameters of the fertilizer particles and to establish the ball of fertilizer particles. The geometric model and the geometric model of the fertilizer plant are used to determine the contact model of the fertilizer particles and the optimal time step. In order to meet the suitable width of 0.8 m, the rotational speed of the centrifugal disc is about 300 rpm. The walking speed of the fertilizer plant and the centrifugal disc leaf are preliminarily analyzed through the EDEM simulation of the fertilizer passing through the tea garden. The influence of single factor, blade bias angle and single factor on the variation coefficient of particle distribution was analyzed. At the same time, the population distribution of the fertilizer particles, the change of single particle velocity, the change of force and the change of displacement were analyzed. The simulation results show that the coefficient of variation is smaller when the walking speed is 0.6 m/s, the bias angle is 30 degrees and the number of the blade is 4. According to the analysis of the distribution of fertilizer particles, it is known that the vertical uniformity of the fertilizer particle distribution is better and the lateral uniformity is poor during the fertilization process. Through the analysis of the velocity of the fertilizer particle, the change of force and displacement, the velocity of the fertilizer particles decreases rapidly, the force becomes larger and the displacement is larger. The change slows slowly, which indicates that the feeding port of the fertilizer plant has the effect of buffering the flow velocity of the fertilizer particles, avoiding the impact of the high speed fertilizer particle flow on the centrifugal disc. (4) the experiment of the effect of the fertilizer and the optimization of the working parameters show that the coefficient of variation is smaller when the walking speed is 0.6 m/s, the bias angle is 30 and the number of the blade is 4. In order to explore the effect of the interaction of the three factors on the uniformity of fertilization and the optimal working parameters, a bench test was carried out by using the two regression orthogonal rotation center combination design test method with three factors and three levels, and the number of leaves, the bias angle and the walking velocity were established on the basis of the results of the test data. The regression model of number is used to optimize the target function under the constraints of various factors, and the optimal results are tested by field test. The optimization results are as follows: the number of leaves is 5, the bias angle is 15.72o, the walking speed is 0.61 m/s, and the distribution variation coefficient reaches the minimum value at this time, which is 10.30%. field test. It is shown that the fertilizer uniformity of the tea plantation device is better under the optimal parameters. The average relative error of the measured value and the predicted value is 10.15%. The maximum relative error is 22.14%. compared with the non optimized fertilizer plant. The optimized working parameters have improved the uniformity of the fertilizer. This paper has designed and developed a tea garden special. The working parameters of a fertilizer plant were used and its working parameters were optimized, and the bench and field experiments showed that the centrifuge dressing device had better uniformity and could be applied to the tea garden under the optimized working parameters.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S224.2

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