Journal of Thermophysics and Heat Transfer最新文献_第5页

Experimental Assessment of Hypersonic Convective Heat Transfer Augmentation due to Surface Roughness 高超音速对流传热因表面粗糙度而增强的实验评估

IF 2.1 4区工程技术 Q2 Physics and Astronomy

Journal of Thermophysics and Heat Transfer

Pub Date : 2024-03-30 DOI: 10.2514/1.t6893

Peter R. Forsyth, Chris Hambidge, Matthew McGilvray

Although engineering correlations exist for the effects of small-scale roughness on heat transfer and shear stress, the complexity of flow physics for elements whose height exceeds the sonic line of hypersonic boundary layers is largely unknown. Additionally, the superposition of multiple scales of roughness in largely unexplored. This study investigates the heat transfer augmentation of two scales of patterned roughness, both individually and combined, where the large-scale roughness exceeds 20% of the boundary-layer height. These mimic technical roughnesses from the original experiments from Nikuradse low-speed experiments. The experiments were undertaken in a Ludwieg tunnel at a nominal Mach number of 5 and unit Reynolds number of [Formula: see text]. Determination of the Stanton numbers were performed by combining measurements of the freestream total temperatures with the measurement of the heat transfer from calorimeter and thin-film heat transfer gauges. Results indicate trends toward bulk heat transfer augmentation of order 20, 40, and 50% with increased [Formula: see text] for the small-, large-, and multiscale roughness patterns tested, respectively. For the large-scale roughness pattern investigated, significant heat transfer suppression was measured in the troughs between the elements; enhancement was measured to be substantial on the peaks, with notable difference distinguished between the spans and the intersections of the elements.

虽然小尺度粗糙度对传热和剪应力的影响存在工程相关性，但对于高度超过高超声速边界层声速线的元素，流动物理的复杂性在很大程度上是未知的。此外，多尺度粗糙度的叠加在很大程度上也是未知的。本研究调查了两种规模的图案化粗糙度（单独和组合）对热传递的增强作用，其中大规模粗糙度超过边界层高度的 20%。这些粗糙度模仿了尼库拉德塞低速实验中的原始技术粗糙度。实验在 Ludwieg 隧道中进行，名义马赫数为 5，单位雷诺数为 [公式：见正文]。斯坦顿数的测定是通过测量自由流的总温度与热量计和薄膜传热计的传热测量相结合进行的。结果表明，在测试的小型、大型和多尺度粗糙度模式中，随着[计算公式：见正文]的增加，散热量分别增加了 20%、40% 和 50%。对于所研究的大尺度粗糙度模式，在元素之间的波谷处测得了明显的传热抑制；在波峰处测得了显著的传热增强，在元素的跨度和交叉点之间有明显的差异。

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