Computational Fluid Dynamics Analysis of the Transient Cooling of the Boiling Surface at Bubble Departure
Computational Fluid Dynamics Analysis of the Transient Cooling of the Boiling Surface at Bubble Departure
复制标题
气泡离开时沸腾面瞬态冷却的计算流体动力学分析
DOI：
10.1115/1.4036572
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发表时间：
2017
影响因子：
--
通讯作者：
B. Niceno
中科院分区：
文献类型：
--
作者：
G. Giustini;S. Walker;Yohei K. Sato;B. Niceno
通过热通量分割的沸腾的大尺度计算流体动力学（CFD）建模依赖于被认为是重要的热传递模式的经验和半机械表示。一种这样的模式，“淬火”，是指将冷水带到加热壁附近，以重新填充由离开的蒸汽泡占据的体积。这是模拟在经典的热通量分区方法使用的半机械处理的基础上理想化的瞬态热传导到液体从一个完美的传导基板。在本文中，我们应用现代界面跟踪CFD方法来模拟蒸汽气泡的生长和离开，试图从机械上（在CFD模型的限制范围内）评估与气泡离开相关的单相传热。这是这种机械建模的主要动机之一，洞察力的发展和量化的提供，以改善必要的经验成分规模建模。计算表明，长期以来的“淬火”模型中使用的基本上所有的热通量分区处理体现了显着高估这部分的热传递，由一个因素，也许是10.30。当然，在热通量分配处理中的各个模型的集合已经被整体地细化和调整，并且单个子模型在数值上不正确并不特别令人惊讶。在实践中，在各种子模型中的不准确性之间有很多抵消，这些子模型的总体表现令人惊讶地好。我们建议的方式，这种更健全的基础量化的“淬火热传递”可能会考虑在组件规模建模。
Component-scale computational fluid dynamics (CFD) modeling of boiling via heat flux partitioning relies upon empirical and semimechanistic representations of the modes of heat transfer believed to be important. One such mode, “quenching,” refers to the bringing of cool water to the vicinity of the heated wall to refill the volume occupied by a departing vapor bubble. This is modeled in classical heat flux partitioning approaches using a semimechanistic treatment based on idealized transient heat conduction into liquid from a perfectly conducting substrate. In this paper, we apply a modern interface tracking CFD approach to simulate steam bubble growth and departure, in an attempt to assess mechanistically (within the limitations of the CFD model) the single-phase heat transfer associated with bubble departure. This is in the spirit of one of the main motivations for such mechanistic modeling, the development of insight, and the provision of quantification, to improve the necessarily more empirical component scale modeling. The computations indicate that the long-standing “quench” model used in essentially all heat flux partitioning treatments embodies a significant overestimate of this part of the heat transfer, by a factor of perhaps ∼30. It is of course the case that the collection of individual models in heat flux partitioning treatments has been refined and tuned in aggregate, and it is not particularly surprising that an individual submodel is not numerically correct. In practice, there is much cancelation between inaccuracies in the various submodels, which in aggregate perform surprisingly well. We suggest ways in which this more soundly based quantification of “quenching heat transfer” might be taken into account in component scale modeling.