全量秸秆地免耕机播碎秸均匀抛撒机理研究与机构优化

The key technique problems to be solved, which aiming at breaking straw barriers and achieving high-quality, smooth straw-smashing, back-throwing and no-tillage planting under full straw mulching field is straw-smashing and uniformity-scattering technology.Taking effectively applied domestic “straw-smashing and lifting-for-delivering and back-throwing” no-tillage planter and typical rice varieties in rice-wheat rotation area as research objects.Aiming at solving the problems of low qualified rate for scattering width and high non-uniformity of straw mulching during the operation process of the uniformity-scattering device of the no-tillage planter, the dynamic simulation model of straw-smashing and uniformity-scattering rigid-flexible coupling system was inosculated and built by applying some theories and methods, such as Pro/E three-dimensional modeling and CFD-DEM for gas-solid two-phase flow.On this basis, dynamic simulation analysis, high-speed photography analysis and bench test analysis were combined, the kinematics and dynamics behavior of the operation procedure was researched, the interaction relationship between operation quality and uniformity-scattering components was explored, the influence mechanism of operation quality and the control strategy was revealed as well.Technological methodologies were integrated, including multi-objective digital simulation optimization, multi-factor experimental optimization and bench verification test, digital model of simulation system and the prediction model of operation qualities were established, synthetical optimum design method of the mechanism was obtained finally, realizing the optimal combination of structural configuration, structural parameters and operational parameters for straw-smashing and uniformity-scattering device.This study will provide theoretical basis and data support for the technology upgrading and components optimization of straw-smashing and uniformity-scattering implemented by no-tillage planter under full straw mulching field.

碎秸均匀抛撒技术是破除秸秆障碍、实现全量秸秆地高质顺畅免耕机播须破解的关键技术难题。以在我国全量秸秆地有效应用的“碎秸拾输跨越抛撒”免耕播种机及稻麦轮作区典型水稻品种为研究对象，针对其碎秸均匀抛撒机构作业过程中碎秸抛撒有效幅宽合格率低、覆秸不均匀度高等问题，应用Pro/E三维建模和CFD-DEM气固两相流理论与方法，融合构建碎秸秆-均匀抛撒机构刚柔耦合系统动力学仿真模型；动力学仿真分析、高速摄影分析与台架试验分析等相结合，研究作业过程动力学行为特性，探明作业质量与抛撒机构特征参数的内在关系，揭示作业质量影响机理和控制策略；融合多目标数字仿真优化、多指标试验优化与台架验证试验等技术方法，构建仿真系统数字化模型和作业质量预测数学模型，取得机构综合优化设计方法，实现机构结构组配、结构参数和作业参数的最佳组合。研究结论为全量秸秆地免耕机播碎秸均匀抛撒技术提升和机构优化提供理论基础与数据支撑。

碎秸均匀抛撒技术是破除秸秆障碍、实现全量秸秆地高质顺畅免耕机播须破解的关键技术难题。目前，有关碎秸均匀抛撒机构作业过程的认知尚未达到理论水平，对其作业机理研究和认识还很粗浅，机构的结构与参数优化方法和依据不足，严重制约了机构创新水平和作业质量。本项目以我国稻麦轮作区典型水稻品种秸秆为研究对象，获取了主产区小麦播种期典型水稻秸秆的形态特征和机械力学特性。确定了碎秸均匀抛撒作业原理与工艺流程，完成了碎秸均匀抛撒机构的优化设计并构建了三维虚拟样机模型，通过FLUENT软件对机构内部气流场进行了仿真模拟和分析，利用EDEM软件构建了碎秸柔性颗粒群体模型，运用CFD-DEM耦合方法建立了能有效描述碎秸均匀抛撒作业过程的碎秸秆-均匀抛撒机构刚柔耦合系统仿真模型。并开展了碎秸均匀抛撒作业过程的动力学仿真分析，解析了碎秸均匀抛撒作业受力和运动行为特征。运用理论分析法推导出碎秸均匀抛撒作业的抛送提升、气力跨越、壁压喷射、击散撒铺等不同阶段的动力学方程，明确了碎秸群团与碎秸均匀抛撒机构相互作用机理。构建了全量秸秆地免耕机播碎秸均匀抛撒试验台并开展台架试验，运用高速摄影分析法，揭示了碎秸抛撒过度分散、超幅宽重叠覆盖、成群成团率高、局部过量覆盖等作业质量产生过程。运用刚柔耦合系统多目标数字仿真分析法，探明了碎秸均匀抛撒机构不同结构参数和运动参数对作业性能的影响。系统开展了多因素多指标响应面试验和正交试验研究，建立了能预测抛撒作业幅宽合格率、抛撒不均匀度等作业指标的多因素数学模型，探明了各因素显著性水平、主次作用顺序与影响规律，通过多目标综合优化获取了碎秸均匀抛撒作业质量提升途径和机构综合优化设计方法。本研究可弥补全量秸秆地免耕机播碎秸均匀抛撒技术基础研究工作的缺失和不足，为我国全量秸秆地高质顺畅免耕播种技术创新和设备研发提供理论依据和新方法。