超临界压力下碳氢燃料在竖直圆管内对流换热实验研究

Experimental Investigation on Convection Heat Transfer of Hydrocarbon Fuels at Supercritical Pressures in Vertical Tubes

采用超临界压力碳氢燃料作为冷却剂的再生冷却技术是超声速燃烧冲压发动机的一种重要热防护技术。本文以工程碳氢燃料为工质,在内径2 mm的竖直圆管内进行了不同流向、流量、压力、热流密度条件下的对流换热实验研究。结果表明,在较高进口Re数条件下,相同热流密度时,向上流动和向下流动工况的壁温分布没有明显差别;在较低进口Re条件下,向上流动工况的局部壁温远高于对应向下流动工况,发生传热恶化。研究表明该碳氢燃料的临界Bo*数判据为3×10^(-7)。拟合得到适用于该碳氢燃料的对流换热关联式。

Hydrocarbon fuels at supercritical pressures are being considered as coolants to meet the cooling requirements of future high-performance aircraft with regenerative cooling systems. This paper presents experimental investigations on convection heat transfer of a particular real fuel at supercritical pressures in vertical tubes with inner diameters of 2 mm, and effects of flowing direction, mass flux, pressure and heat flux were studied. The wall temperature distributions of upward and downward flow were almost the same with conditions of same heat flux and relatively high inlet Reynolds number, while heat transfer deterioration was observed in upward flow with conditions of low Reynolds numbers, which resulted in higher local wall temperature. The threshold of Bo＊ was found to be 3.0× 10^-7, which was slightly different from former works. A new convection heat transfer correlation was obtained based on experimental data.