Transport of Interfacial Area Concentration in Two-Phase Flow
Transport of Interfacial Area Concentration in Two-Phase Flow
复制标题
两相流中界面面积浓度的传递
DOI：
10.5772/33899
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
T. Morii
中科院分区：
文献类型：
--
作者：
I. Kataoka;Kenji Yoshida;M. Naitoh;H. Okada;T. Morii
气液两相流热工水力特性的准确预测对提高核反应堆的性能和安全性具有重要意义。为了分析两相流现象，人们提出了各种模型，如均相模型、滑移模型、漂移通量模型和双流体模型。在这些模型中，双流体模型（石井（1975），Delhaye（1968））被认为是最精确的模型，因为该模型考虑了气-液界面处的相相互作用而单独处理每一相。因此，目前许多核反应堆安全性最佳估计程序都广泛采用双流体模型。在双流体模型中，建立了各相的平均质量、动量和能量守恒方程。各相的守恒方程不是相互独立的，而是通过气液界面的质量、动量和能量传递项强耦合的。界面传递项是双流体模型中的特征项，以界面浓度（单位体积两相流的界面面积）的形式给出。因此，对界面浓度的准确认识对双流体模型预测的准确性至关重要，国内外学者对界面浓度进行了大量的实验和分析研究。在基于双流体模型的常规代码中，界面面积浓度在本构方程中根据取决于两相流的流态的气泡或液滴的韦伯数给出（Ransom等人（1985），Liles等人（1984））。然而，近年来，更准确和多维的预测两相流的先进设计的核反应堆。为了满足改进预测的需要，有必要通过求解输运方程来给出界面面积浓度本身。因此，近年来，国内外对界面区输运的模型、分析和实验研究都十分活跃
The accurate prediction of thermal hydraulic behavior of gas-liquid two-phase flow is quite important for the improvement of performance and safety of a nuclear reactor. In order to analyze two-phase flow phenomena, various models such as homogeneous model, slip model, drift flux model and two-fluid model have been proposed. Among these models, the two-fluid model (Ishii (1975), Delhaye (1968)) is considered the most accurate model because this model treats each phase separately considering the phase interactions at gas-liquid interfaces. Therefore, nowadays, two-fluid model is widely adopted in many best estimate codes of nuclear reactor safety. In two-fluid model, averaged conservation equations of mass, momentum and energy are formulated for each phase. The conservation equations of each phase are not independent each other and they are strongly coupled through interfacial transfer terms of mass, momentum and energy through gas-liquid interface. Interfacial transfer terms are characteristic terms in two-fluid model and are given in terms of interfacial area concentration (interfacial area per unit volume of two-phase flow) Therefore, the accurate knowledge of interfacial area concentration is quite essential to the accuracy of the prediction based on two-fluid model and a lot of experimental and analytical studies have been made on interfacial area concentration. In conventional codes based on two-fluid model, interfacial area concentration is given in constitutive equations in terms of Weber number of bubbles or droplets depending upon flow regime of two-phase flow (Ransom et al. (1985), Liles et al. (1984)). However, recently, more accurate and multidimensional predictions of two-phase flows are needed for advanced design of nuclear reactors. To meet such needs for improved prediction, it becomes necessary to give interfacial area concentration itself by solving the transport equation. Therefore, recently, intensive researches have been carried out on the models, analysis and experiments of interfacial area transport throughout the world