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Numerical Analysis of the Structure of Gas-Solid turcbulene by Using LES

气固湍流管结构的大涡模拟数值分析

基本信息

批准号：
07650205
负责人：
TANAKA Toshitsugu
金额：
$ 1.28万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650205/
关键词：
Multiphase Flow Gas-Solid Flow Turbulence Numerical simulation LES 数値スミュレーション

项目摘要

1.LES of downward gas-solid flows in a vertical channelNumerical smuations with two-way couping were performed for downward particle laden tutbulent flows in a verticul channel. Fluid motion was culculated by using LES with the same models as in single phase flows and the motin of individual particles by the Lagrangian method. Particleparticle collisin was taken into considertion.The present simulation showed that fluid turbulence is modified by particles but quantitatively did not get a good agreement with the measurement.It was found that the effects of particle-particle collisinon on particle diffusion is large even at low ppaticle volume fraction of the order O (10-4), and that the predicted paticle fluctuation velocity in transverse direction is as two times as that without particle-particle collisimon.the predicted particle fluctuation velocies agreed well with the experiment by Kulick et al. (1994). By visualizing the calculated flow field the relation between the particle distribution and the streak structure was studied. It was found that particles tend to concentrate to the low speed streaks.2.Structure of paticle clusterThe results of LES shown that particles tend to form particle clauds caused by the streak structure. It is known that particles form dense clusters and affect turbulent structure largely when particle concentration increases. The structure of particle cluster is also simulated numerically. The characteristic structures both in two-dimensional and three dimensional fields were found. It was found that the spatial scale of cluster increases with increasing particle diameter.

1.垂直流道内气固两相下行流动的大涡模拟研究对垂直流道内下行气固两相流进行了双向耦合数值模拟。流体运动计算采用与单相流相同模型的大涡模拟，并用拉格朗日方法计算单个颗粒的运动。模拟结果表明，颗粒对流体的湍流有一定的修正作用，但定量上与测量结果不太吻合。结果表明，颗粒-颗粒间的相互作用对颗粒扩散的影响很大，即使在O(10-4)量级的低颗粒体积分数下，颗粒横向的脉动速度是无颗粒碰撞时的两倍。(1994年)。通过将计算的流场可视化，研究了颗粒分布与条纹结构之间的关系。结果表明，粒子有向低速条带聚集的趋势。2.粒子团的结构大涡分析结果表明，由于条带结构的原因，粒子容易形成颗粒云。众所周知，当颗粒浓度增加时，颗粒形成致密的团簇，并对湍流结构产生很大影响。对粒子团簇的结构也进行了数值模拟。发现了二维场和三维场的特征结构。结果表明，团簇的空间尺度随着颗粒直径的增大而增大。