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首页> 外文学位 >Vibrationally-Fluidized Granular Flows: Impact and Bulk Velocity Measurements Compared with Discrete Element and Continuum Models.
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Vibrationally-Fluidized Granular Flows: Impact and Bulk Velocity Measurements Compared with Discrete Element and Continuum Models.

机译：振动流化颗粒流：与离散元模型和连续体模型相比，冲击力和体速度的测量结果。

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摘要

A new laser displacement probe was developed to measure the impact velocities of particles within vibrationally-fluidized beds. The sensor output was also used to measure bulk flow velocity along the probe window and to provide a measure of the media packing. The displacement signals from the laser sensors were analyzed to obtain the probability distribution functions of the impact velocity of the particles. The impact velocity was affected by the orientation of the laser probe relative to the bulk flow velocity, and the density and elastic properties of the granular media. The impact velocities of the particles were largely independent of their bulk flow speed and packing density.;Both the local impact and bulk flow velocities within a tub vibratory finisher were predicted using discrete element modelling (DEM) and compared to the measured values for spherical steel media. It was observed that the impact and bulk flow velocities were relatively insensitive to uncertainties in the contact coefficients of friction and restitution. It was concluded that the predicted impact and bulk flow velocities were dependent on the number of layers in the model. Consequently, the final DE model mimicked the key aspects of the experimental setup, including the submerged laser sensor. The DE method predictions of both impact velocity and bulk flow velocity were in reasonable agreement with the experimental measurements, with maximum differences of 20% and 30%, respectively.;Discrete element modeling of granular flows is effective, but requires large numerical models. In an effort to reduce computational effort, this work presents a finite element (FE) continuum model of a vibrationally-fluidized granular flow. The constitutive equations governing the continuum model were calibrated using the discrete element method (DEM). The bulk flow behavior of the equivalent continuum media was then studied using both Lagrangian and Eulerian FE formulations. The bulk flow velocities predicted by the Lagrangian approach were in good agreement with those obtained using DEM simulations over a wide range of tub wall amplitudes. The local impact velocity distribution predicted by the DEM was also compared to the continuum model using the shear rate as a measure of the granular temperature.
机译：开发了一种新的激光位移探头，以测量振动流化床中颗粒的撞击速度。传感器输出还用于测量沿探针窗口的总体流速并提供介质填充的度量。分析来自激光传感器的位移信号，以获得粒子撞击速度的概率分布函数。冲击速度受激光探头相对于整体流速的方向以及颗粒介质的密度和弹性特性的影响。颗粒的撞击速度在很大程度上与它们的整体流速和堆积密度无关;;桶振动抛光机内的局部撞击速度和整体流速均使用离散元模型（DEM）进行了预测，并与球形钢的测量值进行了比较媒体。观察到，冲击和整体流速对摩擦和恢复接触系数的不确定性相对不敏感。结论是，预计的撞击速度和整体流速取决于模型中的层数。因此，最终的DE模型模仿了实验装置的关键方面，包括水下激光传感器。冲击速度和整体流速的DE方法预测与实验测量值基本吻合，最大差异分别为20％和30％。；颗粒流的离散元建模是有效的，但需要较大的数值模型。为了减少计算量，这项工作提出了振动流化颗粒流的有限元（FE）连续体模型。使用离散元方法（DEM）校准控制连续体模型的本构方程。然后使用拉格朗日和欧拉有限元公式研究了等效连续介质的整体流动特性。通过拉格朗日方法预测的整体流速与在大范围的桶壁振幅范围内使用DEM模拟获得的流速非常吻合。还使用剪切速率作为颗粒温度的度量，将DEM预测的局部冲击速度分布与连续模型进行了比较。

著录项

  • 作者

    Hashemnia, Kamyar.;

  • 作者单位

    University of Toronto (Canada).;

  • 授予单位 University of Toronto (Canada).;
  • 学科 Mechanical engineering.;Mechanics.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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