波纹润滑体表减粘降阻特性及耦合仿生研究

The energy and environment crisis has become more and more serious , so adhesion problems is a serious impact on the efficiency and energy consumption of the agricultural machinery, but the traditional techniques and methods of resistance reduction have the defects of low efficiency, complex structure, etc al. This project choose the typical soil animals - earthworms as the bionic prototype, and bionic study on resistance reduction. The shape, structure, size, distribution and combination pattern of the earthworm lubrication unit are studied by means of the modern observation, testing, and analysis tools. Lubrication law of the earthworm body surface is discuses in different soil environment, preparation of the lubricating fluid and earthworm surface sample, which is similar to the earthworm mucous secretions, and research of the resistance reduction characteristic of earthworm surface by adhesion test under the conditions of lubrication, then find out key coupling parameters of the ripple - lubricating surface of earthworm. Design the functional surface coupled with lubrication, form, structure by engineering bionics method. Investigate the effect of the ripple surface and biological lubrication on the reduction resistance characteristics, establish the mathematical model of the lubricating fluid flow, velocity, and soil adhesion resistance. The research results can provide new theories and methods for the resistance reduction, which has greater scientific significance and prospects of engineering applications.

随着能源和环境危机的加深，降低农机触土部件的粘附和阻力，提出减粘降阻的新理论和方法，设计生产出高效率、低能耗的农机具势在必行。针对现有减粘降阻技术和方法存在效率低、结构复杂等缺陷，本项目以典型的土壤动物—蚯蚓为仿生原型，开展蚯蚓体表润滑脱附减阻及仿生研究。项目应用现代观察、测试和分析手段研究蚯蚓体表润滑单元的形状、结构、尺寸、分布及组合模式，探讨不同土壤环境下蚯蚓体表的润滑规律，配制与蚯蚓体表液性能相近的润滑液，制备蚯蚓体表试样，通过粘附力试验研究蚯蚓体表试样在润滑条件下的脱附减阻特性，提取波纹润滑体表的降阻关键耦元。利用工程仿生学原理，设计润滑、形态、结构多元耦合的仿生功能表面，探讨波纹体表以及生物润滑对仿生耦合功能表面降阻特性的影响规律，建立润滑液流量、流速与土壤粘附阻力间数学模型。研究成果可为地面机械触土部件减粘降阻研究提供新的理论和方法。

以赤子爱胜蚓为研究对象，根据蚯蚓的运动特性，制备了收缩态、静息态、舒张态三种试样，利用体视显微镜及其图像分析软件对蚯蚓体表形貌进行分析，提取其特征参数；利用接触角测量仪对蚯蚓体表接触角进行测量，分析其体表润湿性。由分析可知，蚯蚓体表形貌属于典型的波纹形非光滑结构：体节与节间沟组成的环节结构，形成一级宏观波纹形非光滑结构；皮肤表面分布着大量的交错细纹，形成二级微观波纹形非光滑结构。蚯蚓体表不同部位的非光滑程度各不相同：体部纹理小而密，非光滑单元密度较大；头部纹理大而稀，非光滑单元密度较小。不同状态的蚯蚓体表形貌大体类似，其非光滑单元体的特征参数有所不同：头部舒张态、静息态、收缩态结构单元体宽度和高度之比分别为1.65：1：0.78和0.23：1：1.27；体部舒张态、静息态、收缩态结构单元体宽度和高度之比分别为1.65：1：0.81和0.33：1：1.28。舒张时，非光滑单元密度减小；收缩时，非光滑单元密度增大；静息时，非光滑单元密度居中。采用3D打印的方法加工出仿生试样，通过润滑试验研究波纹体表的减阻性能，结果表明：蚯蚓波纹自润滑体表具有良好的降阻效果，前进阻力随着前进速度的增加而减小；随着润滑液流速的增加先减小后趋于不变；前进阻力与正压力成正比；在土壤含水率为22.2%，润滑液流速为2.5ml/min的条件下，降低阻力范围在3.29N-24.93N，减阻率为22.65%到34.89%之间。为进一步探究这三个因素影响规律及因素之间的交互作用，进行三元二次正交旋转组合试验，对回归系数进行检验得出，影响前进阻力的试验因素的主次顺序为：正压力＞润滑液流速＞前进速度，且3个因素对前进阻力的影响显著，同时润滑液流速与前进速度之间存在交互作用。