Abstract To ameliorate the thermal management of a regenerative cooling system in an advanced engine, the turbulence characteristics and entropy generation in a buoyancy-driven supercritical hydrocarbon fuel flow are numerically explored in detail. Several common buoyancy criteria (Gr/Re2, Gr/Re2.7 and Grq/Grth) are established and a three-dimensional numerical model is solved with an advanced LES model. The turbulence characteristics demonstrate that the complex and anisotropic transport properties dramatically redistribute the flow structure and thermal field and the buoyancy-induced production, P b = − g ρ u j ' ‾ , is strongly related to the heat transfer regime. The thermal characteristics, ρ ( u i h s ‾ − u i ‾ h s ‾ ) , indicate that the laminar flow weakens the wall-normal turbulent heat flux, and the buoyancy-driven flow is responsible for the change of stream-wise turbulent heat flux. Based on the second law of thermodynamics, the two typical irreversible entropy generations are discussed, and interestingly, the existing oscillations enlarge the diffusion of local heat entropy and promote the wider heat transfer. The results provide a methodological guidance for thermal management of engines cooling systems.

中文翻译：

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浮力驱动的超临界燃料流中热振荡现象的传输和热力学特性

摘要 为了改善先进发动机再生冷却系统的热管理，对浮力驱动的超临界碳氢燃料流中的湍流特性和熵产生进行了详细的数值研究。建立了几种常见的浮力标准（Gr/Re2、Gr/Re2.7 和 Grq/Grth），并用先进的 LES 模型求解了三维数值模型。湍流特性表明复杂和各向异性的输运特性显着地重新分配了流动结构和热场，浮力引起的产生 P b = - g ρ uj ' ‾ 与传热方式密切相关。热特性 ρ ( uihs ‾ − ui ‾ hs ‾ ) 表明层流削弱了壁面法向湍流热通量，浮力驱动的流动是造成流向湍流热通量变化的原因。基于热力学第二定律，讨论了两种典型的不可逆熵产生，有趣的是，现有的振荡扩大了局部热熵的扩散，促进了更广泛的传热。结果为发动机冷却系统的热管理提供了方法学指导。