【作者】 高娜娜；

【导师】 张东兴；

【作者基本信息】 中国农业大学 ， 农业机械化工程， 2014， 博士

【摘要】 我国黄淮海地区广泛采用小麦-玉米一年两熟的种植模式,小麦茬地上免耕播种玉米时面临小麦秸秆、根茬等堵塞免耕播种机作业部件导致晾籽、播种质量差、工作效率低等问题。目前在用的主动防堵式玉米免耕播种机功耗大、土壤扰动量大,而被动防堵式免耕播种机防堵效果差,严重影响作业质量和效率。本文基于小麦秸秆与防堵机构相互作用机理提出拨草和分草相结合的防堵思路,创新研制出驱动滚筒与分禾栅板组合式防堵机构,实现低耗、高效、高适应性防堵。主要结论和研究成果如下：(1)基于小麦秸秆与防堵机构相互作用机理,首次提出环量绕流拨草和边界层分草相结合的防堵思路,以拨草取代切草,有效防堵的同时显著降低功耗；创新研制出驱动滚筒与分禾栅板组合式防堵机构,驱动滚筒在流场中具有良好的绕流性能,保证在作业过程中不间断地拨草,有效清除种带上的秸秆,分禾栅板防止其再次落回种沟,从而创造清洁的种床,保证播种质量。(2)依据边界层理论、有环量绕流等流体流动特性,分析小麦秸秆与防堵机构相对运动时发生分离的特点,推导出流线型物体分离点靠后、形状阻力小。设计地轮驱动抛物线型滚筒拨草,凸形分禾栅板防止播种圆盘受秸秆影响产生晾籽。初步试验表明,驱动滚筒与分禾栅板组合式防堵机构能有效清除播种机前方秸秆并创造良好的种床。(3)采用SolidWorks的配置功能建立具有不同速比λ、杆数z和半径r等显著影响驱动滚筒作业效果的滚筒参数模型,在Adams中进行运动学仿真,结果表明,速比、杆数和直径与滚筒拨草程度均成正比,进一步分析得出直径150mm的5杆滚筒在速比为1.24时具有良好的拨草效果。田间试验与仿真结果一致,试验结果表明配备有驱动滚筒的免耕播种机各项作业指标符合相关标准要求。(4)分禾栅板将前方滚筒甩出的秸秆分流,避免回落入种沟,同时引导秸秆至相邻种行间远离种带,创造清洁种床。通过CFD软件对分禾栅板形状进行仿真得出凸形分禾栅板的分流能力优于其他流线型,分禾杆曲率半径对分草效果影响显著。基于流体经过不同参数的分禾杆时速度分量及壁面切应力大小的比较,得出分禾栅板张角35。、曲率半径750mmm时,分流效果较好。(5)应用驱动滚筒与分禾栅板组合式防堵机构在河北、山东和河南等地进行田间试验。结果表明本防堵机构通过性良好,作业效率高,平均土壤扰动率为17.8%,平均种带秸秆清洁率为81.1%,晾籽率、播种深度合格率、施肥深度合格率和种肥间距合格率分别为1.1%、95%、91.7%、93.3%,能满足玉米免耕播种的农艺要求。更多还原

【Abstract】 Wheat-corn two crops a year is the main planting patterns in Huanghuai region in China. Blockage, exposed seeds, sowing depth inconsistencies and other issues are major problems which affect the quality of sowing seriously exist in two-crops-a-year areas in North China. The active anti-blocking mechanism has great consumption and soil disturbance, while the passivity anti-blocking mechanism shows poor efficiency and adaptability. A new idea of pushing and separating straw was proposed based on the research of principle between wheat straw and anti-blocking mechanism. An innovative design was developed that was a driven rotary drum and passive residue separating device anti-blocking mechanism to prevent clogging with low consumption, high efficient and high adaptability. The main conclusions and results from the study are as follows:(1) On the basis of principle between wheat straw and anti-blocking mechanism, a new idea of pushing and separating straw was proposed. Cutting straw was replaced by pushing them to reduce power consumption while preventing clogging. An innovative design was developed that was a driven rotary drum and passive residue separating device anti-blocking mechanism. The drum pushed straw continuously and removed them out of seed bed when the planter sowing. The residue separating device prevented straw dropping on the seed bed to guarantee planting quality.(2)The interaction between wheat straw and anti-blocking mechanism and the separation characteristics of them were researched based on boundary layer theory and circulation flow around. The following conclusions can be drawn that streamline body has small shape resistance, and separation point was latter, the program was determined that ground wheel drove rotary drum to push the straw and separating device separated the straw threw by the drum. Preliminary results showed that the driven rotary drum and passive residue separating device anti-blocking mechanism can remove straw and create clean seed bed efficiently.(3)Models were established which have different parameters of ratio, number of bars and diameter by SolidWorks configuration features. The kinematics simulation in Adams showed that ratio, number of bars and diameter are directly proportional to the effect extent of poking straw. The results of further analysis indicated that the optimum parameters of the drum will be:transmission ratio of1.24, maximum diameter of150mm and number of bars of5for the rotary drum. Field trial results were found to be in an agreement with the simulation results and that no-till planter with rotary drums can accord the relevant standards about sowing.(4) The functions of separating device were separating the straw threw by the rotary drum in front of it, avoiding the straw falling into the seed bed, and leading straw placing on adjacent planter rows. Fluent simulation showed that convex shape was the most suitable appearance of separating device than others. Some parameters affected the separating results, such as opening angle, inlet velocity, and radius of curvature. Research on x-velocity component and distribution of wall shear stress were conducted when separating device was working with different parameters. The results showed that the optimum parameters of the separating device will be:opening angle of35°and curvature radius of750mm. (5) Field tests were conducted in Henan province, Hebei province and Shandong province for the planter with driven rotary drum and passive residue separating device anti-blocking mechanism. Field experiments demonstrated that the anti-blocking mechanism had good pass ability and high efficiency. The rate of soil disturbance and the rate of cleaning on seed bed were17.8%and81.1%respectively. The rate of exposed seed, the percent of pass in seed depth, fertilization depth and the spacing between seed and fertilization were1.1%,95%,91.7%,93.3%respectively. Various performance indicators had met the state standards and agronomic requirements.更多还原