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首页> 外文期刊>International Journal of Heat and Mass Transfer >Relationship between turbulent structures and heat transfer in microfin enhanced surfaces using large eddy simulations and particle image velocimetry
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Relationship between turbulent structures and heat transfer in microfin enhanced surfaces using large eddy simulations and particle image velocimetry

机译：大型涡模拟和颗粒图像测速技术在微翅片增强表面中湍流结构与传热之间的关系

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Internally enhanced surfaces such as micro-fins are an important class of heat transfer enhancement in commercial applications. Many research papers discuss the design and optima of these surfaces. However, most previous studies have demonstrated only the macro relationship between the geometries of the micro-fins and heat transfer. The need for a deeper understanding of these fins arose from some currently unsolved problems that limit future development of enhanced surfaces. First, why are increases of heat transfer larger than area increases in micro-finned tubes in most cases? Second, why do internally micro-finned tubes typically have lower heat-transfer-enhanced ratios in laminar and transition flows? This work presents a novel method to analyze the detailed relationship between flow characteristics and heat transfer for one type of micro-fin. The goal of the paper was not to find a new Reynolds number-based correlation, but to find flow patterns responsible for heat transfer enhancement and understand the mechanisms that cause this. First, this paper introduces comprehensive experimental measurements including particle image velocimetry (Ply), measurement of the heat transfer coefficient and accuracy of pressure-drop measurements, all used to validate numerical approaches. Validated large eddy simulations (LES) are then used to predict flow characteristics and coherent structures (Q criterion). The numerical simulation includes both heat conduction in the metal structure and heat convection on the solid-fluid interface. Finally, the paper documents how the flow structures link with the enhancement of heat transfer in the micro-finned duct. (C) 2019 The Authors. Published by Elsevier Ltd.
机译：内部增强的表面（例如微翅片）是商业应用中重要的一类传热增强。许多研究论文讨论了这些表面的设计和优化。然而，大多数先前的研究仅证明了微翅片的几何形状与热传递之间的宏观关系。需要进一步了解这些鳍片的原因是一些目前尚未解决的问题，这些问题限制了增强表面的未来发展。首先，为什么在大多数情况下传热的增加大于微翅片管的面积增加？其次，为什么内部微翅片管通常在层流和过渡流中具有较低的传热增强比？这项工作提出了一种新颖的方法来分析一种类型的微翅片的流动特性与传热之间的详细关系。本文的目的不是要找到新的基于雷诺数的相关性，而是要找到负责传热增强的流动模式并了解引起这种情况的机理。首先，本文介绍了全面的实验测量，包括粒子图像测速（Ply），传热系数的测量和压降测量的准确性，所有这些都用于验证数值方法。经过验证的大涡模拟（LES）然后用于预测流动特性和相干结构（Q准则）。数值模拟包括金属结构中的热传导和固体-流体界面上的热对流。最后，本文记录了流动结构如何与微翅片管中传热的增强联系在一起。 （C）2019作者。由Elsevier Ltd.发布

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