多向扰流换热管管内传热与流动特性数值模拟

Numerical simulation of heat transfer and flow characteristics in multi-directional turbulent heat transfer tubes

采用Realizable k-espilon湍流模型对不同雷诺数下的多向扰流换热管进行数值模拟,首先在光滑管中进行数值模拟,并与经验公式进行对比,验证了该数值方法的可靠性;其次研究了该换热管的结构参数及雷诺数的变化对努塞尔数和阻力系数的影响,进而分析出同一雷诺数下槽深比、节距比的变化对湍流动能和出口温度分布的影响,最后归纳出努塞尔数和阻力系数随结构参数及雷诺数变化的准则关联式。结果表明:随着结构参数的变化,多向扰流换热管的传热与流动性能都会发生显著的变化;当节距比和雷诺数不变时,努塞尔数、阻力系数、湍流动能都随着槽深比的增大而增大;当槽深比、雷诺数不变时,努塞尔数、阻力系数、湍流动能随节距比的增大而减小。研究表明多向扰流传热特性优于光滑管,可以起到较好的强化传热作用,准则关联式可为强化换热提供理论指导。

The Realizable k-espilon turbulence model was used to simulate the multi-directional turbulent heat transfer tubes with different Reynolds numbers.Firstly, the numerical simulation was carried out in the smooth tube and compared with the empirical formula to verify the reliability of the numerical method.The effects of the structural parameters of the heat transfer tube and the variation of Reynolds number on the Nusselt number and the drag coefficient were studied.The influence of the groove depth ratio and the pitch ratio on the turbulent flow energy and the outlet temperature distribution under the same Reynolds number was analyzed.Finally, the criterion correlation of Nusselt number and drag coefficient with structural parameters and Reynolds number is summarized.The results show that the heat transfer and flow properties of the multi-directional spoiler heat transfer tubes change significantly with the change of structural parameters.When the pitch ratio and Reynolds number are constant, the Nusselt number, drag coefficient and turbulent flow energy increase with the increase of the groove depth ratio;when the groove depth ratio and the Reynolds number are constant, the Nusselt number, drag coefficient, and turbulent flow energy decrease with the increase of the pitch ratio.The research shows that the multi-directional spoiler heat transfer characteristics are better than those of the smooth tube, which has a better heat transfer enhancement function.The criterion correlation can provide theoretical guidance for enhanced heat transfer.