基于DPM模型求解自由下落颗粒羽流卷吸空气量

发布时间：2018-01-24 02:13

本文关键词： 粉尘离散相模型羽流卷吸空气量自由沉降　出处：《环境工程学报》2017年04期 　论文类型：期刊论文

【摘要】：为深入了解自由下落颗粒羽流卷吸空气的特性,对氧化铝颗粒从出口直径为5 mm的圆形孔中自由下落的气固两相流场进行了数值模拟研究。依据RNG k-ε模型求解气相雷诺时均N-S方程并进行离散化处理,采用DPM模型跟踪单个粒子以求解颗粒的运动方程,并通过SIMPLE双向耦合,对自由下落颗粒羽流流动特性进行数值模拟。结果表明:自由下落颗粒羽流卷吸空气气相速度在羽流中心线上处于最大值,随着径向距离的增大速度值明显地减小,直到距离中心线30 mm处,之后速度的变化趋于稳定;颗粒在净质量力作用下沿质量力方向首先作加速运动,之后下落速度u_p随着下落高度的变化趋于平缓,羽流末端颗粒运动基本遵守颗粒自由沉降规律;羽流卷吸空气量随着下落高度的增加而增大,其规律与颗粒群模型给出的结果高度吻合。通过比较分析发现,采用DPM模型很好的解决了对颗粒相运动方程的求解并可获取颗粒运动轨迹,对于自由下落颗粒羽流特性的分析不失为一种有效而可行的方法。
[Abstract]:In order to understand the characteristics of free-falling particle plume entrainment air. The numerical simulation of gas-solid two-phase flow field of alumina particles falling freely from a circular hole with a diameter of 5 mm at the outlet was carried out according to RNG. The K- 蔚 model is used to solve the gas phase Reynolds average N-S equation and discretize it. The DPM model is used to track a single particle to solve the equation of motion of the particle, and the two-way coupling is carried out through SIMPLE. The numerical simulation of the free falling particle plume is carried out. The results show that the air vapor velocity of the free falling particle plume is the maximum at the center of the plume. With the increase of radial distance, the velocity value decreases obviously until 30 mm from the center line, and then the variation of velocity tends to be stable. Under the action of net mass force, particle accelerates first along the direction of mass force, then the falling velocity u p tends to be gentle with the change of falling height, and the particle movement at the end of plume basically obeys the law of particle free settlement. The air volume of plume entrainment increases with the increase of falling height, which is in good agreement with the result given by the particle group model. The DPM model is used to solve the equation of particle phase motion and the trajectory of particle motion can be obtained. It is an effective and feasible method to analyze the plume characteristics of free falling particles.
【作者单位】：西安建筑科技大学环境与市政工程学院;西安建筑科技大学材料与矿资学院;
【基金】：国家自然科学基金重点资助项目(51238010) 国家创新群体科学基金项目(51221865)
【分类号】：X964
【正文快照】： 工业生产过程中经常需要对固体颗粒物料进行装卸、包装或转运等处理工作,仅依靠重力作用使得颗粒物料以自由下落的方式进行操作成为既节能又高效的方法。由于颗粒物料自由下落以及与料堆或地等接触面的撞击时常常伴随大量的固体微粒的形成[1],根据微粒的粒径不同将会以飘尘、

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