同种材料颗粒碰撞电MOSIAC模型及数值模拟 Alternative Title The MOSIAC model and numerical simulation of contact electrification by collision of homogenous particles 李桂宣 Thesis Advisor 谢莉 2013-05-25 Degree Grantor 兰州大学 Place of Conferral 兰州 Degree Name 硕士 Keyword 同种材料 球板斜碰 摩擦面积 碰撞带电机理 面电荷Mosaic分布 多次碰撞 Abstract 首先开展了球-板碰撞带电量实验研究。发现同种材料球和板斜碰后球板会带电，带电量的极性与材料有关，带电量的大小与板倾角有关，随着倾角的增大先增加后减小，当倾角约45°时，碰撞电量达到最大，是正碰撞电量的6-8倍。通过球板斜碰过程的动力学分析，发现球板碰撞后的带电量与碰撞过程中球与板的摩擦面积成正相关。 基于Baytekin等观测的面电荷Mosaic分布以及Apodaca提出的Donor、Acceptor面电荷类型和电荷转移概率假设，提出了两颗粒碰撞带电量理论模型，导出了两颗粒一次碰撞和多次碰撞后的带电量理论计算公式，该公式表明初次碰撞带电量与参与碰撞接触面积差成正比、与电荷转移概率以及面电荷密度成正比。利用该公式不仅可以预测不同大小两颗粒一次碰撞后各自带电极性相反、等大颗粒一次碰撞不带电等现象，而且可以模拟两同种颗粒一次碰撞后带电量随着粒径比的增大先增大后减小、随相对碰撞速度增大而增大的实验规律；还可以模拟球-板斜碰带电量随板倾角先增加后减小的实验规律；同时发现两颗粒多次碰撞后带电量随着碰撞次数增加逐渐达到饱和，饱和电量与颗粒粒径比、碰撞颗粒粒径以及相对碰撞速度相关。 开展了两种粒径多颗粒系统碰撞电模拟和多粒径多颗粒系统碰撞电模拟，结果表明，颗粒系统频繁碰撞使得颗粒带电量最终到达饱和，考虑碰撞角度的影响能够明显减小饱和碰撞次数。电荷极性与颗粒尺寸及其分布相关，给定颗粒系统颗粒带电量服从一定分布。 综上所述，本论文从实验方面探究了颗粒碰撞的角度明显影响碰撞电量，理论方面解释了颗粒碰撞带电规律，并在此基础上模拟了多颗粒的碰撞带电，这些都将有利于同种材料颗粒带电的理解与探究。 Other Abstract Since the impact angle could affect contact electrification, we carried out experiment study on the charge carried by ball obliquely impacting with plate, the ball and the plate have the same materials. The ball and plate after impact would be charged, while the polarity depends on the materials. And the magnitude of charge is related to angle of inclination of plate, which first increases and then decreases with the increase of angle. When the angle is 45 degree the charge maximizes, which is 6-8 times as much as that of direct impact. By analysis of ball-plate oblique impact dynamics, it is found the charge and friction area are perfect correlation. Based on the charged surface Mosaic distribution observed by Baytekin and the hypothesis proposed by Apodaca, a statistical model to compute the net charge of electrified particle after a single collision and multiple collisions are established, respectively. The model shows the net charge carried by the electrified particles depends on the difference between the two surfaces’ areas involved in collision contact and gives results in good agreement with experiment results. The charge arrived at maximum when the ratio of radius is about 0.7. We introduce ball-plate oblique impact equivalent to multiple collisions and find the calculation is qualitatively consistent with experimental phenomena. With increasing of the number of collisions the charge reaches saturation gradually, magnitude of which depends on ratio of particles, particle sizes and the relative collision velocity. The thesis simulates the charge of multi-particle collisions including systems of two particle sizes and multiple sizes. The results show the charge gradually reaches saturation with the increase of the number of collisions; and it is found impact angle can reduce the saturation number of collisions effectively. The polarity of charge depends on the particle sizes and the distribution of size. in addition, the magnitude of charge has a certain distribution. In summary, the impact angle significantly affects the charge through the experiment; and the mosaic model is established to explain the contact electrification due to collisions of particles; then the electrification due to multi-particle collisions is simulated. Therefore, the study will be conducive to understand and explore the contact electrification by collision of homogenous particles. URL 查看原文 Language 中文 Document Type 学位论文 Identifier https://ir.lzu.edu.cn/handle/262010/225911 Collection 土木工程与力学学院 Recommended CitationGB/T 7714 李桂宣. 同种材料颗粒碰撞电MOSIAC模型及数值模拟[D]. 兰州. 兰州大学,2013.
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