二维气固两相后台阶流动的大涡模拟

摘要/Abstract

摘要： 采用大涡模拟、Smagorinsky亚格子应力模型及SIMPLER 算法,数值模拟了气固两相流体后台阶流动中各物理量的输运特性。首先,讨论了后台阶流动中分离涡旋结构和回流区长度随入口速度分布、台阶上游长度的变化情况;然后,用颗粒追踪法,计算了不同入流速度、不同粒径的颗粒在后台阶流场中的扩散行为。计算结果表明,选择抛物线型入口速度分布,能比较好地模拟真实的后台阶流动；在气固两相流动中,颗粒运动是气相涡旋和固相颗粒惯性共同作用的结果,随着颗粒粒径的增加,颗粒对气体涡旋的跟随性逐渐变弱,而其惯性特性表现得越来越显著。当大量颗粒由不同粒径组成时,颗粒的扩散将具有选择性,显示出多尺度耦合现象。所得结果有助于解释风成地貌形态的形成机理,也可以为风沙流风洞模拟实验设计提供一定的理论指导。

关键词: 大涡模拟, 两相流, 后台阶流动, 颗粒弥散

Abstract: The parameters of two dimensional backward-facing step gas-particles flows are studied numerically based on large-eddy simulation, Smagorinsky SGS stress model and SIMPLER algorithm. First, the variations of the reattachment positions of two dimensional backward-facing step with different upper flow channel and inlet velocities are revealed. Then, the solid particles with different diameters are traced by particle trajectory method, and the particle dispersion characteristics at different inlet velocities are disclosed. Results reveal that the particle motion is mainly controlled by its inertia force on the particles with diameter larger than 100 μm, and it is essentially controlled by air force for the particles with diameter less than 20 μm, and by both forces with transitional diameters. The research shows that large-eddy simulation is a powerful method to study the gas-particle two phase flows, and it can be used to guide construction of porous fence and performance of the gas-particle flow experiments in laboratory.

Key words: large-eddy simulation, two phase flow, backward-facing step flow, particle dispersion

中图分类号:

O359
X169

武生智;赵玉军;刘晓军. 二维气固两相后台阶流动的大涡模拟[J]. 中国沙漠, 2011, 31(5): 1093-1097.

WU Sheng-zhi;ZHAO Yu-jun;LIU Xiao-jun. Large-Eddy Simulation of Two Dimensional Backward-Facing Step Gas-Particle Flows[J]. JOURNAL OF DESERT RESEARCH, 2011, 31(5): 1093-1097.

参考文献

[1]董治宝,郑晓静.中国风沙物理研究五十年(Ⅱ)[J]. 中国沙漠,2005,25(6):795-815.
[2]丁国栋.风沙物理学中两个焦点问题研究现状与未来研究思路刍议[J].中国沙漠,2008,28(3):395-398.
[3]尹晓惠.我国沙尘天气研究的最新进展与展望[J].中国沙漠,2009,29(4):728-733.
[4]高卫东,袁玉江,刘志辉,等.新疆沙尘源状况及其沙尘气溶胶释放条件分析[J].中国沙漠,2008,28(5):968-973.
[5]胡赞远,吕志咏.风沙运动中沙粒阻力的数值研究[J].中国沙漠,2009,29(1):46-49.
[6]韩邦帅,薛娴,王涛,等.沙漠化与气候变化互馈机制研究进展[J].中国沙漠,2008,28(3):410-416.
[7]Armaly B F,Durst F.Experimental and theoretical investigation of backward-facing step flow[J].Journal of Fluid Mechanics,1983,127:473-496.
[8]刘应征,朴英守,成亨镇.后台阶分离再附湍流流动的实验研究[J].上海交通大学学报,2005,39(5):810-812.
[9]王小华,樊洪明,何钟怡.后台阶流动的数值模拟[J].计算力学学报,2003,20(3):361-365.
[10]王兵,张会强,虞建丰,等.后台阶分离流动中大涡结构演变的数值模拟[J].力学季刊,2003,24(2):166-173.
[11]任凯锋,王希麟,张会强.后台阶气固两相流动的PDPA实验[J].清华大学学报(自然科学版),2005,45(8):1099-1102.
[12]王兵,张会强,王希麟.颗粒在大涡结构中的弥散[J].力学学报,2005,37(3):105-108.
[13]罗坤,樊建人,岑可法.气固两相流动中颗粒扩散的转捩现象[J].科学通报,2006,51(23):2810-2817.
[14]刘阳,周力行,徐春晓,等.后台阶气固流动的双流体大涡模拟和二阶矩两相湍流模型的验证[J].化工学报,2008:2485-2489.
[15]陶文铨.数值传热学[M].西安:西安交通大学出版社,2001.
[16]何子干,倪汉根.大涡模拟法的二维形式[J].水动力学研究与进展,1994,9(1):30-36.