插秧机船板表面微观结构仿生减阻研究

发布时间：2018-05-11 10:16

本文选题：草鱼鳞片 + 仿生减阻　；参考：《沈阳农业大学》2017年硕士论文

【摘要】：船板是水稻插秧机的重要触泥部件之一,在水田泥水环境作业过程中,其与泥水相接触形成较大的滑行阻力,使得能源浪费严重,同时也降低了作业效率。可见,对于减小插秧机船板流体阻力的研究,具有重要的意义。本文在国家自然科学基金项目:插秧机船板底面鳞片形仿生微结构的减阻机理研究(51305282)的资助下,以草鱼鳞片表面微观结构作为生物原型,设计了具有鳞片型微结构的仿生表面,并分析其减阻特性。将这种微结构仿生应用到水稻插秧机的船板上,进一步研究了船板底面泥浆的流动摩擦学特性及其减阻性能。主要研究内容与结论如下:通过对鳞片微结构的观察分析,获得了鳞片单元体的形态、结构特征参数及整体分布规律,提取了各区域微观结构的主要尺寸。选取鳞片后区具有规则分布的微观结构作为生物原型,建立了具有鳞片型仿生表面的三维简化模型。通过对具有鳞片型微结构仿生表面的FLUENT模拟,分析了仿生表面的困水、漩涡等流体力学特性,并揭示了减阻机理。即:在微结构前表面附近形成了低速的涡漩,稳定了边界层内流体的运动,进而形成了低速稳定态的"困水"区域,起到了流体润滑的作用,形成了明显的减阻效果。仿生样件阻力拖拽试验结果表明:这种微结构在低速时具有较好的减阻效果,且随着来流速度的增加,减阻率呈现出降低的趋势。在v=0.66 m·s-1时,减阻效果最好,最大减阻率为2.805%。通过对仿生样件的FLUENT模拟及阻力拖拽试验研究,优化出鳞片微结构的最优参数组合,即鳞嵴高度为0.05mm,鳞嵴宽度为0.45 mm,相邻鳞嵴之间的距离为0.20 mm,来流速度为0.70 m·s-1。鳞嵴高度对仿生表面的减阻效果具有显著性的影响,而其它因素影响并不显著。通过正交试验获得了影响船板底面滑行阻力因素的主次顺序为船板样式船板样件的配重前进速度,得到的最优参数组合为前进速度v=0.4 m.s-1、配重为0.7 kg、仿生船板样件,此时减阻效果最佳,最大减阻率为22.90%。通过对仿生船板样件在泥浆介质中的Fluent模拟,获得了船板样件表面附近的泥浆压力及速度的分布情况,得到仿生船板样件的最佳减阻率为28.50%。本研究通过对插秧机船板表面微观结构的仿生减阻研究,改善了船板底面的摩檫学特性,实现减阻。该研究是结构仿生学在水田机械领域的拓展研究,也为在工程机械、农业机械、交通运输等领域的仿生减阻研究提供了参考。
[Abstract]:The ship board is one of the important parts of rice transplanter. In the process of working in paddy field and mud water environment, the contact between ship board and mud water forms a great sliding resistance, which causes serious energy waste and reduces the working efficiency at the same time. Therefore, it is of great significance to reduce the fluid resistance of transplanter. In this paper, with the aid of the project of National Natural Science Foundation: the study on drag reduction mechanism of scale-like biomimetic microstructures on the bottom surface of transplanters, a biomimetic surface with scale-like microstructures was designed with the surface microstructure of grass carp scales as a biological prototype. The characteristics of drag reduction are analyzed. The microstructural biomimetic method was applied to the ship board of rice transplanter, and the flow tribological characteristics and drag reduction performance of the mud on the bottom surface of the ship board were further studied. The main contents and conclusions are as follows: through the observation and analysis of the microstructures of the scales, the morphology, structural characteristic parameters and the overall distribution of the scales are obtained, and the main dimensions of the microstructures in each region are extracted. The microstructures with regular distribution in the posterior region of scales were selected as biological prototypes, and a simplified three-dimensional model with scale-like biomimetic surfaces was established. By FLUENT simulation of biomimetic surface with scale structure, the hydrodynamic characteristics of bionic surface, such as water trap and vortex, are analyzed, and the mechanism of drag reduction is revealed. That is, a low velocity vortex is formed near the front surface of the microstructure, which stabilizes the movement of the fluid in the boundary layer, and then forms the "trapped water" region in the low speed stable state, which plays the role of fluid lubrication and forms an obvious drag reduction effect. The drag and drag test results of bionic samples show that the drag reduction effect of the microstructures is better at low speed, and the drag reduction rate decreases with the increase of incoming flow velocity. The maximum drag reduction rate is 2.805 when VX is 0.66 m / s ~ (-1) and the maximum drag reduction rate is 2.805 m / s ~ (-1). Based on the FLUENT simulation and drag test of the biomimetic samples, the optimum parameters of the scale microstructures were optimized, namely, the height of the scales was 0.05 mm, the width of the scales was 0.45 mm, the distance between adjacent scales was 0.20 mm, and the flow velocity was 0.70 m ~ (-1). The scale ridge height had a significant effect on drag reduction of bionic surface, but other factors did not. Through the orthogonal test, the main and secondary order of the factors affecting the skidding resistance on the bottom surface of the ship's plate is obtained, which is the weight forward speed of the ship's plate model, the optimum parameter combination is the advance speed (v) 0.4 m.s-1, the counterweight is 0.7 kg, and the bionic ship plate sample. At this time, drag reduction effect is the best, the maximum drag reduction rate is 22.90. The distribution of mud pressure and velocity near the surface of the bionic ship plate sample is obtained by Fluent simulation in the mud medium. The optimum drag reduction rate of the bionic ship plate sample is 28.50. Based on the study of biomimetic drag reduction of the surface microstructure of the ship plate of the transplanter, the friction characteristics of the bottom surface of the ship plate are improved and the drag reduction is realized. This study is an extension of structural bionics in the field of paddy field machinery, and also provides a reference for bionic drag reduction research in construction machinery, agricultural machinery, transportation and other fields.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S223.91

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