Heat transfer augmentation due to flow pulsation in a channel with teardrop-shaped dimples investigated by large eddy simulation

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL International Journal of Heat and Fluid Flow Pub Date : 2024-09-19 DOI:10.1016/j.ijheatfluidflow.2024.109579

Tsubasa Yamamoto, Akira Murata, Kento Inokuma, Kaoru Iwamoto

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Abstract

This study investigated effects of flow pulsation on heat transfer performance of the surface with teardrop-shaped dimples. The flow structures and heat transfer characteristics were simulated by large eddy simulation with a Lagrangian dynamic sub-grid scale model. The cases of steady flow and pulsating flow (the Strouhal number of 0.3 and rms velocity amplitude normalized by bulk velocity of 0.14) were examined for dimple inclination angle of 30 deg, 45 deg, and 60 deg with in-line arrangements and for the bulk Reynolds number of 25,000. Surface-averaged results indicated that the flow pulsation increased the Nusselt number ratio by 9–12 %, the friction factor by 18–21 %, and the heat transfer efficiency index by 3–6 %. Using the phase-averaged results, it was clarified that the increased Nusselt number was due to the appearance and disappearance of flow-separation bubbles induced by the flow pulsation at the leading edge of inclined dimples and the time-averaged swirling flow intensity was well correlated with the surface-averaged Nusselt number and the friction factor.

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通过大涡流模拟研究水滴形凹槽中的流动脉动导致的传热增强

本研究探讨了流动脉动对水滴形凹陷表面传热性能的影响。采用拉格朗日动态子网格尺度模型，对流动结构和传热特性进行了大涡度模拟。研究了稳定流和脉动流（斯特劳哈尔数为 0.3，按体积速度归一化的均方根速度幅值为 0.14）的情况，分别针对 30 度、45 度和 60 度的凹陷倾角，以及 25,000 的体积雷诺数。表面平均结果表明，流动脉动使努塞尔特数比增加了 9-12%，摩擦因数增加了 18-21%，传热效率指数增加了 3-6%。利用相平均结果，可以明确努塞尔特数的增加是由于倾斜凹槽前缘的流动脉动诱发了流动分离气泡的出现和消失，而时间平均漩涡流强度与表面平均努塞尔特数和摩擦因数有很好的相关性。

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来源期刊

International Journal of Heat and Fluid Flow 工程技术-工程：机械

CiteScore

5.00

自引率

7.70%

发文量

131

审稿时长

33 days

期刊介绍： The International Journal of Heat and Fluid Flow welcomes high-quality original contributions on experimental, computational, and physical aspects of convective heat transfer and fluid dynamics relevant to engineering or the environment, including multiphase and microscale flows. Papers reporting the application of these disciplines to design and development, with emphasis on new technological fields, are also welcomed. Some of these new fields include microscale electronic and mechanical systems; medical and biological systems; and thermal and flow control in both the internal and external environment.