【摘要】 对于超临界压力CO2在垂直圆管(din=2 mm)内高进口雷诺数(Re=9 000)条件下向上流动时的对流换热进行了数值模拟。通过与实验数据进行对比来验证湍流模型的可靠性,并研究变物性和浮升力对壁面温度和湍动能的影响。结果表明:在热流密度较高的情况下,向上流动时出现了局部换热恶化和换热强化现象,这主要归因于浮升力对湍动能分布的影响;采用LB湍流模型能较好地模拟这种换热现象;在热流密度较低的情况下,未出现上述换热现象。更多还原

【Abstract】 Convection heat transfer of CO2 at supercritical pressure in a vertical circular tube(din=2 mm) at high inlet Re(about 9 000) was investigated numerically to analyze the effects of the variation of the physical properties and buoyancy on the wall temperature and the turbulent energy.The results show that in the case of high heat fluxes the local heat transfer deterioration and enhancement during the upward flow due to the strong influence of buoyancy result in change of the turbulent energy distribution.Simulations using the LB turbulence model correspond well with the experimental data in upward flow.In the case of low heat fluxes the phenomenon of heat transfer deterioration or enhancement was not observed.更多还原