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首页> 外文期刊>International Journal of Heat and Mass Transfer >Heat flow analysis for natural convection within trapezoidal enclosures based on heatline concept
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Heat flow analysis for natural convection within trapezoidal enclosures based on heatline concept

机译：基于热线概念的梯形罩内自然对流的热流分析

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摘要

Heat flow patterns in the presence of natural convection within trapezoidal enclosures have been analyzed with heatlines concept. In the present study, natural convection within a trapezoidal enclosure for uniformly and non-uniformly heated bottom wall, insulated top wall and isothermal side walls with inclination angle φ have been investigated. Momentum and energy transfer are characterized by stream-functions and heatfunctions, respectively, such that streamfunctions and heatfunctions satisfy the dimensionless forms of momentum and energy balance equations, respectively. Finite element method has been used to solve the velocity and thermal fields and the method has also been found robust to obtain the streamfunction and heatfunction accurately. The unique solution of heatfunctions for situations in differential heating is a strong function of Dirichlet boundary condition which has been obtained from average Nusselt numbers for hot or cold regimes. Parametric study for the wide range of Rayleigh number (Ra), 10~3 ≤ Ra ≤ 10~5 and Prandtl number (Pr), 0.026 ≤ Pr ≤ 1000 with various tilt angles φ = 45°, 30° and 0° (square) have been carried out. Heatlines are found to be continuous lines connecting the cold and hot walls and the lines are perpendicular to the isothermal wall for the conduction dominant heat transfer. The enhanced thermal mixing near the core for larger Ra is explained with dense heatlines and convective loop of heatlines. The formation of boundary layer on the walls has a direct consequence based on heatlines. The local Nusselt numbers have also been shown for side and bottom walls and variation of local Nusselt numbers with distance have also been explained based on heatlines. It is found that average heat transfer rate does not vary significantly with for non-uniform heating of bottom wall.
机译：使用热线概念分析了梯形外壳内自然对流情况下的热流模式。在本研究中，已经研究了梯形围护结构内均匀和不均匀加热的底壁，隔热顶壁和等温侧壁（倾斜角为φ）的自然对流。动量和能量传递分别以流函数和热函数为特征，以使流函数和热函数分别满足动量和能量平衡方程的无量纲形式。有限元方法已被用来求解速度场和热场，并且还发现该方法对于准确地获得流函数和热函数是鲁棒的。针对差热情况的热函数的唯一解决方案是Dirichlet边界条件的强大函数，该函数已从热或冷状态的平均Nusselt数获得。在各种倾斜角φ= 45°，30°和0°（平方）下的宽瑞利数（Ra），10〜3≤Ra≤10〜5和普朗特数（Pr），0.026≤Pr≤1000的参数研究）已执行。发现热线是连接冷壁和热壁的连续线，并且这些线垂直于等温壁以进行传导主导的热传递。对于较大的Ra，在芯部附近增强的热混合通过密集的热线和热线的对流回路来解释。基于热线，壁上边界层的形成具有直接的后果。还显示了侧壁和底壁的局部Nusselt数，并且还基于热线解释了局部Nusselt数随距离的变化。对于底壁的非均匀加热，发现平均传热率不会随显着变化。

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