酒窝型U形管内RP-3航空煤油流动及传热特性数值模拟研究

Numerical Simulation Study on Flow and Heat Transfer Characteristics of RP-3 Aviation Kerosene in a Dimple-type U-tube

摘要:

借助 U 形管结构及管壁表面结构优化，可进一步强化对流传热过程，但其流动传热机理和优化设计方法仍需进一步研究。为进一步提升 U 形管强化对流传热特性，结合酒窝表面结构优化的航空煤油空—油换热器 U 形管结构，提出一种航空煤油空—油换热器强化传热方案。通过数值模拟，系统分析 RP-3 航空煤油在高压工况（3~5 MPa）与高热流密度（500~800 kW/m2）下，酒窝型 U 形管的流动传热耦合机制。结果表明：酒窝结构与弯管离心力协同作用，通过诱导逆压梯度和边界层二次流发展，显著增强湍动能，并生成区别于迪恩涡的新型涡系结构；该结构使弯管段努塞尔数达直管的 2.4~3.0 倍，综合传热系数（PEC）为 1.96~2.71，且在增大压力/热流密度或降低流量时进一步优化，展示了酒窝型 U 形管在强化传热方面的显著优势。

Abstract:

To enhance convective heat transfer in the U-tube through surface structure optimization, this study proposes an improved heat transfer design for aviation kerosene air-oil heat exchangers using a dimple-structured U-tube. Numerical simulations were conducted to systematically analyze the coupled flow and heat transfer mechanisms of RP-3 aviation kerosene under high-pressure (3–5 MPa) and high-heat-flux (500–800 kW/m2) conditions. The results demonstrate that the combined effects of dimple structures and centrifugal forces in the bend region induce adverse pressure gradients and promote secondary flows in the boundary layer, significantly amplifying turbulent kinetic energy and generating unique vortex structures distinct from conventional Dean vortices. These dimple-induced vortices propagate toward the tube core, enhancing heat transfer performance. The U-bend section achieves Nusselt numbers 2.4–3.0 times higher than those of straight tubes, with a performance evaluation criterion (PEC) of 1.96–2.71. Notably, increasing operating pressure/heat flux or reducing flow rate further improved PEC values, highlighting the superiority of the dimple-type U-tube in convective heat transfer enhancement through synergistic structural and flow effects.