摘要
为研究内热源存在时多孔介质中流动和传热的特性,采用数值方法对上下底绝热、内外壁存在温差时,竖直套管中带均匀容积热源的多孔介质内的自然对流进行了分析。考查了内、外Rayleigh数之比Rai／Ra、高宽比A及半径比k对流场、温度场以及局部和平均Nusselt数的影响。研究结果表明,Rai／Ra和A较大时,内、外壁面附近分别形成两个逆向环流,温度场出现θ>1的高温区和θ<1的低温区,高温区的范围随Rai／Ra和A的增大而扩大。内壁面局部Nusselt数沿管长先增大后下降,分界点位置随k的减小和A的增大下移;外壁面局部Nusselt数在管上部区域迅速增大。内壁面平均Nusselt数Nui与Rai／Ra的增加呈现负的线性关系。
In order to study the hydrodynarnic and heat transfer characteristics in porous medium with inner heat source, the natural consection in a vertical annulus filled with saturated porous medium is numerically analyzed when the top and bottom in adiabatic condition, and temperature difference existed in inner and outer wall. Effects of Rai/Ra, A and k on the fluid field, temperatur field, local and average Nusselt numbers are investigated. The results show that two reverse circulations appear near the inner and outer wall,high temperature region of (θ>1 and low temperature region of θ<1 occur in the temperature field at relatively high Rai/Ra andA, and the region ofθ> 1 expands with increasing Rai/ Ra and A. The local Nusselt number on inner wall increases at first and then decreases along the axial direction, the zero point moves to lower as k decreases and A increases. In the other hand, the local Nusselt number on outer wall increases rapidly on the upper of annulus. The average Nusselt number on the inner wall decreases linearly as Rai/Ra increases.
出处
《化学工业与工程技术》
CAS
2005年第1期42-45,共4页
Journal of Chemical Industry & Engineering
关键词
内热源
自然对流
多孔介质
竖直套管
数值分析
Inner heat source
Natural convection
Porous media
Vertical annulus
Numerical analysis
