超临界压力RP-3在竖直细圆管内混合对流研究

研究了超临界压力下碳氢燃料航空煤油RP-3在竖直细圆管内混合对流,分析了浮升力及热物性对碳氢燃料在垂直管中对流换热的影响。实验中控制热流密度从200~500 kW/m2变化,进口压力变化范围为3~5 MPa,进口雷诺数从5 000~10 500范围内变化。研究表明:在向上流动情况中进口段存在较为明显的入口效应,换热出现恶化现象,而在向下流动中未出现;对于向上和向下流动,由于热物性的综合影响,换热系数沿流动方向增大;在较低进口雷诺数(Re=5 700)时,对于向下流动,随着浮升力影响的增大,浮升力改变了流体径向速度分布,出现了换热强化;在较高进口雷诺数(Re=10 500)时,浮升力对换热的影响依然显著;判别式Bo*数小于5.6×10-7未能预测浮升力对碳氢燃料换热影响。 

Investigation of mixed convection of supercritical pressure RP-3 in vertical round tube

The mixed convection research of supercritical pressure hydrocarbon aviation fuel RP-3 in vertical tube was conducted and the effects of buoyancy and thermophysical properties on convection was investigated. The wall heat fluxes (200-500 kW/m²), inlet pressure (3-5 MPa) and inlet Reynolds number (5 000-10 500) were maintained in the experiments. The study shows that heat transfer impairment occurrs in inlet region for all upward flow conditions due to buoyancy effects, which is not observed in the downward flow. The heat transfer coefficient increases as the fluid bulk temperature increased as a result of comprehensive effects of thermophysical properties. At lower inlet Reynolds number (5 700), the radial velocity profile changes in downward flow conditions leading to heat transfer enhancement due to buoyancy effects. The buoyancy effects are also significant for higher inlet Reynolds number (10 500). The criterion equation (Bo^* < 5.6×10^-7) failed to evaluate buoyancy effects on hydrocarbon fuel heat transfer.