管内核心流区域对流强化传热强化数值模拟-工程热物理专业论文.docxVIP

华 华 中 科 技 大 学 硕 士 学 位 论 文 I I 摘 要 传热强化技术，由于能使各种换热设备的效率提高、重量和体积减少，一直受 到科技界和工业界的重视。由于上世纪 70 年代的能源危机和国际原油价格的持续上 涨，传热强化技术获得了快速发展。虽然某些受迫流动强化传热技术已得到相当广 泛地应用，但是，它们普遍存在一个问题，大多数的强化传热是基于边界层理论， 因而在传热强化的同时，流动阻力(功耗)增加的更多。为了对此问题做更深入地研究， 寻求传热和流动综合性能较好的强化换热管，本文提出一种新的强化传热观点：核 心流区域强化传热。 为了对强化换热管的性能进行对比分析，本文采用了 Webb 所提出的换热与流动 综合评价标准—PEC，该标准简便实用，物理意义明确，并在换热研究中有着广泛的 使用。 对比三种换热管，即光滑圆管、核心流区域单排杆插入物强化换热管和核心流 区域双排杆插入物强化传热管，模拟计算的方法进行了对比研究。结果表明：在以 水做为流动工质时，核心流区域强化的方式能够很好的改善流场的温度分布状况， 并有效的提高对流换热系数，阻力系数的增加也较小。这种强化换热方式在层流范 围内的效果比在湍流范围内更为明显。 最后，本文应用场协同原理对研究中出现的现象进行了理论分析，并与数值模 拟结果和对比分析结果进行了比较，核心流区域的强化换热方式能够很好的改变流 动换热的场协同角，与数值计算的对流换热 Nu 系数完全相一致，得出了合理的结论。 关键词：核心流区域强化换热，场协同理论，PEC，数值模拟 II II Abstract Technology of enhancing heat transfer, which can improve efficiency of heat exchanger and reduce equipments weight and volume, is always attached importance to by scientists and engineers. After energy crisis in 1970s, technology of enhancing heat transfer is developed greatly. Some technologies of enhancing heat transfer have been applied widely, but there is a similar problem in these technologies, most of them are based on boundary theory, as a result, flow resistances enhancement is faster than heat transfers. We did researches on these problem and proposed new theory: heat transfer enhancement in the core flow. For comparison of the results, a standard advanced by Webb about heat transfer and fluid resistance is brought forward. The standard is simple and very convenient and has more specific physical meaning than other standards. It is applied widely in study of heat transfer at present. For comparisons of the three kinds of tubes, namely, smooth tube, tube with single row poles inserted and tube with two row poles inserted, the numerical simulations were done. The indicates that, when water is used as working fluid, core-field heat transfer enhancement can improved the temperature field, making the temperature field more uniform. Heat transfer coefficient increased obviously, but the flow resistanc