基于离散元法的外槽轮排肥器工作过程仿真与参数优化

发布时间：2018-11-02 20:00

【摘要】：外槽轮排肥器作为我国目前施肥机械中应用最广泛的排肥器之一,存在排肥量难以精确控制、排肥不均问题。本文以外槽轮工作长度、排肥轴转速、排肥舌开口角度为试验因素,以排肥量及排肥脉动变异系数为评价指标。综合应用离散元法、二次正交旋转响应面试验、外槽轮排肥验证试验,研究外槽轮排肥器工作参数对排肥量及排肥脉动的影响,进而优化关键工作参数组合。本文的主要研究内容及结论如下:(1)肥料颗粒的物理力学参数测量。选取磷酸二铵、尿素、复合肥为研究对象,通过物理学和物料学基础实验,测量肥料颗粒的密度、三轴尺寸、弹性模量、剪切模量、摩擦系数、碰撞恢复系数等参数,为排肥器工作过程的离散元仿真模型提供基础数据。(2)排肥器工作过程离散元仿真模型的建立。通过逆向建模技术建立磷酸二铵、尿素、复合肥颗粒的扫描模型及填充模型,并建立外槽轮排肥装置的三维模型。将外槽轮排肥装置的三维模型、肥料颗粒的填充模型导入离散元软件中设置相关的仿真变量,构建外槽轮排肥工作过程的离散元仿真模型,为后续的研究提供仿真平台。(3)外槽轮排肥器工作参数对排肥量的影响。采用离散元仿真与二次正交回归试验相结合的方法,建立工作参数与排肥量之间的回归函数模型,识别影响排肥量的主次因素。以磷酸二铵、尿素、复合肥为排肥对象时,排肥量离散元仿真试验与试验之间的平均相对误差分别为10.04%、12.73%、9.96%。(4)排肥器工作参数对排肥脉动过程的影响与参数组合优化。建立了排肥器关键工作参数与脉动变异系数之间的回归函数模型,明确影响脉动变异系数的主次因素。通过响应面分析,优化了外槽轮排肥器关键参数组合。试验结果表明,当外槽轮工作长度为45mm、排肥轴转速为55r/min、排肥舌开口角度为22.5°时,排肥脉动变异系数的离散元仿真值与验证试验值分别为10.89%和9.55%,且仿真试验与验证试验的结论一致。
[Abstract]:As one of the most widely used fertiliser in fertilization machinery in our country, it is difficult to control the amount of fertilizer discharge accurately and the problem of unevenness of fertilizer discharge exists. In this paper, the working length of the outer groove wheel, the rotation speed of the discharge shaft and the opening angle of the fat discharge tongue are the experimental factors, and the quantity of fertilizer discharge and the coefficient of variation of the pulsation of the discharge of fertilizer are taken as the evaluation indexes. Based on discrete element method, quadratic orthogonal rotation response surface test and external slot wheel fertilization verification test, the effects of working parameters of external slot wheel fertilizer emitter on the discharge amount and pulsation were studied, and the key working parameters were optimized. The main contents and conclusions of this paper are as follows: (1) Measurement of physical and mechanical parameters of fertilizer particles. The parameters such as density, triaxial size, elastic modulus, shear modulus, friction coefficient and collision recovery coefficient of fertilizer particles were measured by physical and material experiments, including diammonium phosphate, urea and compound fertilizer. It provides the basic data for the discrete element simulation model. (2) the establishment of the discrete element simulation model for the working process of the fertiliser. The scanning model and filling model of diammonium phosphate, urea and compound fertilizer particles were established by reverse modeling technology. The 3D model and the filling model of fertilizer particles are introduced into the discrete element software to set up the relevant simulation variables, and the discrete element simulation model of the working process of the external slot wheel is constructed. (3) the influence of the working parameters of the external slot wheel fertiliser on the amount of fertilizer discharge. Using the method of discrete element simulation and quadratic orthogonal regression test, the regression function model between working parameters and fertilizer discharge is established to identify the primary and secondary factors that affect the amount of fertilizer discharged. When diammonium phosphate, urea and compound fertilizer were taken as fertilizer discharge objects, the average relative error between discrete element simulation test and experiment was 10.04 ~ 12.73g, respectively. 9.96. (4) the influence of the working parameters of the fertiliser on the pulsation process and the optimization of the parameters. The regression function model between the key working parameters and the pulsating variation coefficient of the fertiliser was established, and the primary and secondary factors affecting the pulsating variation coefficient were determined. Based on response surface analysis, the key parameter combination of the external groove wheel fertiliser was optimized. The experimental results show that when the working length of the outer groove wheel is 45mm, the rotation speed of the discharge shaft is 55r / min, and the angle of the tongue opening is 22.5 掳, the discrete element simulation value and the verification test value of the coefficient of variation are 10.89% and 9.55%, respectively. The conclusion of simulation test is consistent with that of verification test.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S224.2

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