多影响因素作用下碳氢燃料跨临界过程换热恶化的数值研究

Numerical study on heat transfer deterioration of hydrocarbon fuel in transcritical process under influence of multiple influencing factors

为深入理解多影响因素作用下碳氢燃料跨临界过程换热恶化的特性,基于开源计算软件OpenFOAM对超临界RP-3的流动换热过程进行数值模拟。采用广义对应状态法则对碳氢燃料替代模型的物性进行计算,湍流模型选用SST(shear stress transport)k-ω湍流模型。与实验数据比较,热流密度为300～400kW/m2内的计算壁温平均误差小于3%。研究分析了换热恶化机理,讨论压力、进口温度、热流密度与质量流量之比对RP-3换热特性的影响。结果表明:拟临界温度附近RP-3热物性的剧烈变化是强制对流下发生换热恶化的主要原因;提高压力、降低热流密度与质量流量之比或减小进口温度是避免流体在拟临界温度附近发生换热恶化的有效措施;提出了换热恶化预测关联式,为主动再生冷却技术提供参考。

In order to deeply understand the heat transfer characteristics of supercritical hydrocarbon fuel in the process of active regeneration cooling,the heat transfer characteristics of supercritical RP-3 were numerically calculated based on the open source software OpenFOAM.The SST(shear stress transport)k-ω turbulence model was used and the physical properties of aviation kerosene alternative fuels were calculated by the generalized corresponding state law.Comparative analyses between numerical and experimental results were used to evaluate the reliability of calculation method,the average error of wall temperature was less than 3% with the heat flux ranging from 300 kW/m^2 to 400 kW/m^2.The mechanism of heat transfer deterioration was analyzed,the effects of pressure,inlet temperature and the ratio of heat flux and mass flow rate on the flow and heat transfer were discussed.Itindicated that the dramatic changes of hydrocarbon fuel physical properties near the pseudo critical temperature were the main cause of heat transfer deterioration under forced convection.Improving the pressure and the ratio of heat flux and mass flow rate or decreasing the inlet temperature were effective measures to avoid the heat transfer deterioration near the pseudo critical temperature.The predictive correlation formula of heat transfer deterioration had been proposed,providing a reference for the regeneration cooling technology.