Effect of crossflow orientations in the impinging jet flow channel on flow and heat transfer enhancement under rotations

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences Pub Date : 2024-10-15 DOI:10.1016/j.ijthermalsci.2024.109478

Natthaporn Kaewchoothong , Thantup Nontula , Chayut Nuntadusit

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Abstract

An experimental and numerical investigation was conducted to elucidate the flow and heat transfer characteristics of a row of impinging jets within a confined, rotating channel. The study focused on a jet Reynolds number (Re_j) of 9,000, examining three distinct crossflow orientations: radially outward (ROCF), radially inward (RICF), and a combined radially outward and inward (ROICF) scheme. Jet-to-impingement surface distances (h/d_j) of 2, 4, and 6 (where dj represents the jet orifice diameter) were considered, along with channel rotation speeds corresponding to Rotation numbers (Ro) from 0 to 0.0046. Heat transfer on the leading and trailing sides of the impinging jets was measured using a steady thermochromic liquid crystal (TLC) technique under constant heat flux conditions. Additionally, RANS simulations were employed to investigate the flow fields associated with the impinging jets. The results reveal that in both the ROCF and RICF schemes, heat transfer, characterized by the Nusselt number, decreases from upstream to downstream for each impinging jet. Increasing the rotation number (Ro) leads to enhanced heat transfer, with the trailing side exhibiting marginally higher values than the leading side. In the ROICF scheme, at h/d_j = 2, a more uniform Nusselt number distribution is observed across all jet holes compared to the ROCF and RICF schemes, and this uniformity increases with higher Ro. However, for h/d_j = 4 or 6, the heat transfer becomes non-uniform and can even deteriorate below the stationary case at high Ro numbers, attributed to the combined effects of Coriolis and centrifugal forces.

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冲击射流流道中的横流方向对旋转条件下流动和传热增强的影响

我们进行了一项实验和数值研究，以阐明在一个封闭的旋转通道内一排撞击射流的流动和传热特性。研究的重点是 9,000 的射流雷诺数 (Rej)，考察了三种不同的横流方向：径向向外 (ROCF)、径向向内 (RICF) 以及径向向外和向内的组合 (ROICF) 方案。考虑了 2、4 和 6（其中 dj 代表射流孔直径）的射流至阻挡面距离 (h/dj)，以及与 0 至 0.0046 旋转数 (Ro) 相对应的通道旋转速度。在恒定热通量条件下，使用稳定热致变色液晶 (TLC) 技术测量了撞击射流前侧和后侧的传热情况。此外，还采用 RANS 模拟来研究与撞击喷流相关的流场。结果显示，在 ROCF 和 RICF 方案中，以努塞尔特数为特征的传热从上游向下游递减。增加旋转数（Ro）可增强传热，尾流侧的传热值略高于前流侧。在 ROICF 方案中，当 h/dj = 2 时，与 ROCF 和 RICF 方案相比，所有喷射孔的努塞尔特数分布更加均匀，并且这种均匀性随着 Ro 的增加而增加。然而，当 h/dj = 4 或 6 时，由于科里奥利力和离心力的共同作用，传热变得不均匀，在高 Ro 值时甚至会恶化到低于静态情况。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Thermal Sciences 工程技术-工程：机械

CiteScore

8.10

自引率

11.10%

发文量

531

审稿时长

55 days

期刊介绍： The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review. The fundamental subjects considered within the scope of the journal are: * Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow * Forced, natural or mixed convection in reactive or non-reactive media * Single or multi–phase fluid flow with or without phase change * Near–and far–field radiative heat transfer * Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...) * Multiscale modelling The applied research topics include: * Heat exchangers, heat pipes, cooling processes * Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries) * Nano–and micro–technology for energy, space, biosystems and devices * Heat transport analysis in advanced systems * Impact of energy–related processes on environment, and emerging energy systems The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.