微距粒子图像测速法测量球床多孔介质单孔流场实验

发布时间：2018-03-08 06:14

本文选题：微距PIV技术　切入点：流场测量　出处：《科学技术与工程》2017年27期 　论文类型：期刊论文

【摘要】：PIV技术是20世纪80年代发展起来的一种瞬态、多点、无接触的流体力学测速方法。它能够在不干扰流场的情况下,实现对流场瞬时和全局测试。试验在现有PIV中添加微距镜头,对多孔介质某一孔隙的流动特征进行检测和分析研究。实验选用的多孔介质是由直径20 mm的水晶玻璃球随机堆积而成,孔隙率为0.592 3,迂曲度为1.33,选用的流体为65%苯甲醇和35%无水乙醇混合液,其折射率须与多孔介质完全匹配。经过微距PIV实验,得到多孔介质某一孔隙内的流场矢量图。分析发现:低雷诺数时,流体流动受外界干扰随机扰动,方向出现波动性,随着雷诺数增加,惯性力增强,干扰和波动性被抑制,流动变得稳定规则,流线为直线;当雷诺数达到154.1时,开始出现局部流线弯曲,因而可以认为此时多孔介质进入流动转捩期,当雷诺数超过214.9时,流动进入完全湍流,全场流动转为不规则流动,同一雷诺数下不同区域流动大小方向不断发生变化,不同雷诺数下同一区域的流场也不相同。同时还发现,不稳定流动可能源于某些未被惯性抑制的随机流动。当雷诺数超过482.2后,横向流动或者旁路流使湍流流动愈益复杂,不同位置交替出现流体的聚团和剥离消散。这些为多孔介质内部流动转捩机制提供了深入认识和新的发现。
[Abstract]:PIV technology is a transient, multi-point, non-contact hydrodynamic velocimetry method developed in 1980s. It can realize instantaneous and global measurement of the flow field without disturbing the flow field. The flow characteristics of a pore in a porous medium are examined and analyzed. The porous media selected in the experiment is composed of 20 mm diameter crystal glass ball stacked randomly. The porosity is 0.5923, the roundness is 1.33, the selected fluid is 65% benzyl alcohol and 35% anhydrous ethanol mixture, its refractive index must match the porous media exactly. The flow vector diagram of a pore in porous media is obtained. It is found that when the Reynolds number is low, the fluid flow is randomly disturbed by external interference and the direction is fluctuated. With the increase of Reynolds number, the inertial force increases, and the disturbance and volatility are suppressed. When the Reynolds number reaches 154.1, the local streamline begins to bend, so it can be considered that the porous media enters the flow transition period, and when the Reynolds number exceeds 214.9, the flow enters into complete turbulence. The full-field flow changed to irregular flow, and the flow direction of different region changed continuously under the same Reynolds number, and the flow field of the same area was also different under different Reynolds number. At the same time, it was also found that, The unstable flow may originate from some random flow which is not suppressed by inertia. When Reynolds number exceeds 482.2, the turbulent flow becomes more complicated by lateral flow or bypass flow. At different locations, fluid clusters and peel dissipations occur alternately, which provide a deep understanding and new discovery for the mechanism of flow transition in porous media.
【作者单位】：内蒙古科技大学能源与环境学院;内蒙古科技大学内蒙古自治区白云鄂博矿多金属资源综合利用重点实验室和省部共建国家重点实验室培养基地;北京工业大学环境与能源工程学院;
【基金】：国家重点基础研究发展(973)计划(2012CB720402) 国家自然科基金(51166010) 内蒙古科技大学创新基金(2011NCL001) 内蒙古应用技术研究与开发资金(20130310) 内蒙古高校创新团队研究计划(NMGIRT1406)资助
【分类号】：O357.3

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