竖直内螺纹管中超临界RP-3航空煤油换热特性数值研究

Numerical Research on Heat Transfer Characteristics of Supercritical RP-3 Aviation Kerosene in Vertical Internally-ribbed Tubes

针对空–油换热器的结构优化应用,开展了竖直内螺纹管中超临界RP-3航空煤油换热特性数值研究。阐述了沿流动方向的传热恶化问题和沿圆周方向螺纹顶部–螺纹底部的非均匀换热机制。通过近壁区流体参数分布情况揭示了传热恶化的原因。讨论了通道截面温度场、流场、湍动能的分布特征,基于螺旋度和二次流强度描述了二次流的影响。探究了运行压力和螺纹数目对换热的影响。实现了换热关联式预测。结果表明:吸热能力下降和湍动能异常减小是第一次传热恶化的原因,类膜态沸腾还会导致第二次传热恶化问题。螺纹结构和变密度耦合产生二次流,螺旋度沿流动方向不断增大,高温区二次流强度与换热状况具有耦合机制。提出的换热关联式有效获得了三种类型内螺纹管中超临界航空煤油的换热预测。

Based on the structural optimization application of air-fuel heat exchanger,numer-ical research on heat transfer characteristics of supercritical RP-3 aviation kerosene in vertical internally-ribbed tubes were carried out.Mechanisms of the heat transfer deterioration along the flow direction and the non-uniform heat transfer of rib top-bottom along the circumferential di-rection were studied.The reason of deteriorated heat transfer was revealed by the fluid param-eters distributions in the near-wall region.The distributions of temperature field,flow field and turbulent kinetic energy in channel cross-sections were discussed,and the secondary flow influ-ence was analyzed based on the helicity and secondary flow intensity.The effects of operating pressure and rib number on heat transfer were investigated.The heat transfer correlation pre-diction was obtained.The results show that the first heat transfer deterioration is due to the decreased heat absorption capacity and the abnormal reduced turbulent kinetic energy,and the pseudo-film boiling leads to the second deteriorated heat transfer.The secondary flow is generated by the coupling of rib structure and variable density,the helicity increases along the flow direc-tion,and there is a coupling mechanism between the secondary flow intensity and heat transfer in the high temperature region.The proposed heat transfer correlations can effectively achieve the heat transfer prediction of supercritical aviation kerosene in three types of internally ribbed tubes.