压力对水平管内超临界碳氢燃料流动换热影响实验

通过实验装置研究了系统压力对水平管内超临界碳氢燃料RP-3流动换热特性的影响规律,并对管内燃油径向热物性变化、浮升力以及热加速对流动换热特性的作用机理进行了分析.结果表明:管内燃油表面传热系数随主流温度升高而增大,不同系统压力下,燃油在相同无量纲温度点热物性变化速率的不同导致了表面传热系数和Nu_x峰值的差异;燃油主流温度与内壁温度之间的差异而导致的热物性差别是造成管内换热规律变化的主要原因,浮升力和热加速作用对换热特性的影响可以忽略;无量纲参数Gr_q/Gr_th可以更好地反映超临界压力碳氢燃料RP-3在水平管内的沿程流动换热特性变化规律. 

Pressure effect on the heat transfer characteristics of hydrocarbon fuel in the horizontal circular tube at supercritical pressures

Experiments were performed to investigate the pressure effect on the heat transfer characteristic of hydrocarbon fuel RP-3 in the horizontal circular tube at supercritical pressures. The mechanisms of heat transfer variation due to the radial thermal property, buoyancy and acceleration effects were discussed as well. The results showed that the heat transfer coefficient increased with the rising fuel bulk temperature. Under different pressures, the fuel thermal property variation''s gradient led to the discrepancies of heat transfer and Nu_x peak points at the same dimensionless bulk temperature. The main reason of the heat transfer distribution was attributable to the radial thermal property gradient due to the temperature discrepancy between the tube inner wall and bulk fuel. However, the buoyancy and acceleration effect were limited in the experiment region. It showed that the dimensionless parameter Gr_q/Gr_th precisely reflected the heat transfer characteristic variation of the supercritical hydrocarbon in the horizontal circular tube.