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以发动机主动再生冷却系统为研究对象,建立了碳氢燃料热物性高精度计算方法,在此基础上对超临界压力下低温甲烷在水平波纹管内的流动换热现象展开数值研究,初步分析了波纹管强化换热机理。进一步系统研究了波纹管节高比、管壁材料导热系数、壁面热流密度、入口压力以及雷诺数对强化换热和阻力特性的影响,并采用综合换热性能评价准则对各种因素的影响进行评价。研究表明:在超临界压力下合理选择波纹管可以显著提升换热能力,消除传热恶化现象,并且不会带来明显的压降损失;存在一个最优波高和最佳雷诺数,使波纹管具有最优的综合换热性能;增大管壁材料导热系数和甲烷入口压力可提高换热能力。
Taking the active regeneration cooling system of the engine as the research object, a high-accuracy calculation method of thermophysical properties of hydrocarbon fuel was established. On the basis of this, a numerical study on the flow heat transfer phenomenon of low temperature methane in a horizontal corrugated tube under supercritical pressure was carried out. Tube to strengthen the heat transfer mechanism. The influences of the section ratio of the corrugated tube, the thermal conductivity of the wall material, the heat flux density of the wall, the inlet pressure and the Reynolds number on the heat transfer enhancement and resistance characteristics were further systematically studied. The influences of various factors on the heat transfer performance evaluation criteria Evaluation. The results show that the reasonable selection of bellows under supercritical pressure can significantly improve the heat transfer capacity and eliminate the heat transfer deterioration without obvious pressure loss loss. There exists an optimal wave height and the optimal Reynolds number so that the bellows With the best overall heat transfer performance; increase the wall material thermal conductivity and methane inlet pressure can improve the heat transfer capacity.