| 筒仓动态卸料过程侧压力模拟与验证 |
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| 引用本文： | 张大英,许启铿,王树明,梁醒培.筒仓动态卸料过程侧压力模拟与验证[J].农业工程学报,2017,33(5):272-278. |
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| 作者姓名： | 张大英 许启铿 王树明 梁醒培 |
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| 作者单位： | 1. 郑州航空工业管理学院土木建筑工程学院,郑州,450015;2. 河南工业大学土木建筑学院,郑州,450001;3. 郑州大学综合设计研究院有限公司,郑州,450002 |
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| 基金项目： | 国家自然科学基金资助项目"基于环境激励的钢筋混凝土立筒群仓动力相互作用机理研究"（51178164）;郑州市科技计划项目"立筒仓的动力测试优化与动力特性研究"（20140586） |
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| 摘 要： | 为了研究立筒仓卸料过程中的侧压力及数值模拟技术,设计了有机玻璃筒仓模型进行试验研究,运用ABAQUS有限元软件中的自适应网格划分技术模拟了筒仓的动态卸料过程。结果表明,筒仓动态侧压力试验值大于静态侧压力,但各测点超压系数不同,在邻近漏斗附近超压系数最大为1.78,其次为仓壁中上部2个测点超压系数达到了1.73和1.61,其他位置超压系数在1.45以内;侧压力模拟值与计算值吻合度较好,静态侧压力两者相对误差绝对值在0.43%~9.92%之间,动态侧压力两者相对误差绝对值在1.14%~9.65%之间,验证了数值模拟技术的可行性;静态和动态侧压力的数值模拟曲线、公式计算曲线、试验曲线或试验拟合曲线都表明,随着测点距筒仓底部高度的增加,侧压力呈下降趋势,即侧压力下大上小,而且静态侧压力模拟曲线与试验曲线变化规律一致,相对误差绝对值在1.83%~9.97%之间;由于试验时压力传感器精度、标定试验误差和试验次数等随机因素的影响,动态侧压力试验曲线不很规则,数值模拟曲线相对平滑,但动态侧压力试验值的拟合曲线与数值模拟曲线变化趋势基本相同,相对误差绝对值在0.28%~9.93%之间。通过观察漏斗附近Mises应力分布图发现,物料卸出前,应力较大点发生在紧邻漏斗附近的仓壁处,卸料开始后,应力较大点即转向漏斗壁中部某范围,而且随着卸料时间的延长,此应力较大点的范围有所增大。
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| 关 键 词： | 筒仓 模型 有限元分析 侧压力试验 动态卸料模拟 |
| 收稿时间： | 2015/11/30 0:00:00 |
| 修稿时间： | 2016/12/30 0:00:00 |
Simulation and experimental validation of silo wall pressure during discharging |
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| Zhang Daying,Xu Qikeng,Wang Shuming and Liang Xingpei.Simulation and experimental validation of silo wall pressure during discharging[J].Transactions of the Chinese Society of Agricultural Engineering,2017,33(5):272-278. |
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| Authors: | Zhang Daying Xu Qikeng Wang Shuming and Liang Xingpei |
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| Institution: | 1. School of Civil Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450015, China;,2. School of Civil Engineering and Architecture, Henan University of Technology, Zhengzhou 450001, China;,3. Zhengzhou University Multi-functional Design and Research Academy Co.. Ltd., Zhengzhou 450002, China; and 2. School of Civil Engineering and Architecture, Henan University of Technology, Zhengzhou 450001, China; |
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| Abstract: | Abstract: Wall pressure especially dynamic wall pressure of the single silo is crucial for the silo design. Therefore, it''s necessary to obtain static and dynamic wall pressures, as well as their change regularity along the silo wall. In view of this, 2 techniques were mainly used in this study containing experimental method and simulation technique in order to solve the aforementioned problem. Apparently, it is difficult and intractable to study and discuss wall pressures of the silo during discharging. Nevertheless, it is direct and efficient to carry out experiment on this issue, so we carried out this test in Structure Laboratory of Henan University of Technology. In this experiment, the test object was a miniature silo model of organic glass due to its transparency to materials. We could clearly observe flow patterns of materials inside the silo. The silo model was full of standard sand, and sensors were pasted on the internal surface of the silo wall to record test data. The static wall pressure was tested after the silo model was filled up, and the dynamic wall pressure was tested during discharging. In order to obtain accurate experimental results, tests with many times had been done. On the other hand, for mutual authentication, ABAQUS software was employed to simulate the flow of material during discharging. The finite element model (FEM) was two-dimensional (2D) model with a rigid line representing the silo wall and a plane representing the material. In this process, surface-to-surface contact was used, and the silo wall and the material boundary were set to the target and contact element respectively. What was more, adaptive mesh subdivision technology was very important, for time duration of material discharging was directly affected, and it lasted 0.25 s in the process. In addition, some phenomena appeared in Mises stress cloud charts. The larger the Mises stress changed from the silo wall to the hopper wall, the larger the stress area on the hopper wall increased over time. Moreover, in order to verify the experimental and numerical results, theoretical formulae in Chinese code were used to calculate static and dynamic wall pressures, and it was verified that the calculated values were large influenced by the wall pressure coefficient. After that, experimental results, simulation results and theoretical values were also obtained and compared with each other. It was shown that dynamic pressures were bigger than the static ones; the maximum overpressure coefficient reached 1.78 at 0.15 m, the second larger overpressure coefficient reached 1.73 at 0.65 m, and thus the dynamic pressures increased by over 70% compared with the static pressures for the 2 measure points. About the other measure points, the overpressure coefficient was less than 1.45, and the minimum was 0.99. The other comparative results showed that the difference between simulated values and theoretical values of the silo wall pressure was small. To some extent, it was more or less different between experimental values and simulated values due to sensor accuracy and calibration test errors, but the variation tendency of static wall pressure was almost the same; in addition the dynamic pressure was affected larger than the static pressure by the above factors, and therefore the experimental curve was a little irregular, while the simulated curve of it was more smooth. And then, some helpful phenomena appeared through data analysis of measure points, for example, dynamic wall pressure amplitude of each measure point was different, and the maximum was next to the hopper; the higher value was nearly in the middle of the silo wall. Through the above analysis, the proposed simulated and experimental method are also feasible to obtain static and dynamic wall pressures of the silo, and the obtained change regularity of pressures along the silo wall is useful for the silo design and further research. |
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| Keywords: | silo models finite element method experimental study on wall pressure simulation technique during discharging |
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