CFD Analysis for Beyond Bubbly Gas-Liquid Two-Phase Flows in a Large Diameter Pipe
"Due to the complexity of multiphase flow phenomena, numerical analysis for multiphase turbulent flow is not as reliable as single-phase computational fluid dynamics (CFD). A literature review has revealed that the current efforts on multiphase flow simulation have focused on small diameter channels under very restricted flow conditions and have been conducted without identifying some important procedures. To expand CFD applications to a wide range of two-phase flow conditions in large diameter channels, this study aims to validate the current CFD models for vertical concurrent air-water two-phase flow simulations beyond bubbly flows. First, a numerical model developed to describe dynamical changes of interfacial area concentration (IAC) of bubbles, known as two-group interfacial area transport equation (2G IATE), is evaluated for a wide range of flow regimes in a large diameter pepe. This evaluation includes examinations of mass and momentum exchange, and interaction mechanisms between gas phases and between gas and liquid phases. Second, the interfacial force closure models, which are a key for the accurate prediction of two-phase flow parameters on the Eulerian-Eulerian framework, are validated and an appropriate choice of closure models for the flow regimes beyond bubbly flows is proposed. Third, CFD models affecting the turbulence mixing effect are compared and the effect of bubble-induced turbulence (BIT) generated by small and large bubbles is investigated. The three important aspects addressed for the validation of the CFD models for high void fraction and high velocity flow conditions in a large diameter pipe are the first effort to validate the current CFD models for beyond bubbly flows and for a large diameter pipe"--Abstract, p. iii
Beyond bubbly flows, CFD, IATE, Interfacial transfer, Large diameter pipe, Two-phase flow, Engineering, Nuclear Engineering
Missouri University of Science and Technology
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