Transient behaviors of mixed convection in a square enclosure with an inner impulsively rotating circular cylinder
Transient behaviors of mixed convection in a square enclosure with an inner impulsively rotating circular cylinder
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带有内部脉冲旋转圆柱体的方形外壳中混合对流的瞬态行为
DOI：
10.1016/j.icheatmasstransfer.2018.08.016
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发表时间：
2018-11
影响因子：
7
通讯作者：
朱祖超
中科院分区：
文献类型：
--
作者：
张炜;魏义坤;窦华书;朱祖超
本文数值研究了不同温度下方形封闭空间与同心圆柱体之间的非稳态混合对流换热。圆柱体的运动是一个过渡过程，其物理过程对于旋转轴的冷却和滑动轴承的润滑等工程应用具有重要意义。它首先保持静止，达到稳态自然对流，然后以恒定的角速度脉冲旋转，达到一个新的最终稳态。尽管已有大量文献对旋转圆柱体的混合对流换热进行了研究，但没有对旋转圆柱体从旋转开始到最终稳定状态的瞬态传热和流动特性进行研究，这限制了对相关流动物理和机理的深入理解。本工作进行了第一次数值研究的目标物理问题。目的是探索混合对流换热的瞬态特性，并确定圆柱旋转和旋转速度（在圆柱表面的切向速度，V0）的流动和传热行为的影响。给出了温度场、平均传热率、局部传热率和速度/温度在某些流动受影响较大区域的时间变化和空间分布，并对结果进行了分析。数值结果首次区分了切向速度对流动的影响：V0 ≤ 1.0时，自然对流作用明显，流动由浮力和切向基于这两种状态，对热量和流量的瞬态行为进行了表征和分类。
This work numerically investigated the unsteady mixed convective heat transfer between a square enclosure and an inner concentric circular cylinder maintained at different temperatures. The cylinder undergoes a transition of motion whose physics is significant for engineering applications such as cooling of rotating shaft and lubricating of journal bearing. It keeps stationary at first and steady-state natural convective flow is achieved, then impulsively rotates at a constant angular velocity and the flow arrives at a new final steady-state. Although the mixed convective heat transfer for rotating cylinder configurations are analyzed in a number of works, the transient behaviors of the thermal and flow characteristics from the onset of cylinder rotation to the final steady-state are not investigated, which restrains the thorough understandings on the relevant flow physics and mechanisms. The present work performs the first numerical investigation on the targeted physical problem. The objective is to explore the transient characteristics of the mixed convective heat transfer, and to identify the effects of cylinder rotation and rotation speed (tangential velocity at cylinder surface,V0) on the flow and heat transfer behaviors. The results are presented and analyzed by the temporal variations and spatial distributions of the thermal field, mean heat transfer rate, local heat transfer rate and velocity/temperature in certain regions where the flow is significantly affected. Our numerical results for the first time identify two flow regimes depending on the tangential velocity:mixed buoyancy-shear stress dominated flowforV0≤ 1.0 where the effect of natural convection is pronounced and the flow is driven by both buoyancy and shear stress from the cylinder surface, andshear stress dominated flowforV0≥ 2.0 where the flow is almost entirely driven by rotating cylinder and heat transfer is realized by conduction. The transient behaviors of the thermal and flow quantities are characterized and categorized based on the two regimes.
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DOI：
10.1142/9789814603584_0003
发表时间：
1998-10
期刊：
--
影响因子：
--
作者：
通讯作者：
--
DOI：
10.1016/j.ijheatmasstransfer.2013.12.081
发表时间：
2014-05-01
影响因子：
5.2
作者：
Liao, Chuan-Chieh;Lin, Chao-An
通讯作者：
Lin, Chao-An
影响因子：
2
作者：
Lei Yang;B. Farouk
通讯作者：
Lei Yang;B. Farouk
DOI：
10.1016/j.icheatmasstransfer.2017.10.015
发表时间：
2018
影响因子：
7
作者：
Wei Zhang;Yi-kun Wei;Xiao-ping Chen;H. Dou;Zuchao Zhu
通讯作者：
Wei Zhang;Yi-kun Wei;Xiao-ping Chen;H. Dou;Zuchao Zhu
影响因子：
2
作者：
N. Ghaddar;F. Thiele
通讯作者：
N. Ghaddar;F. Thiele