高速炉ガス巻込み現象の実規模解析

概要

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To evaluate gas entrainment (GE) phenomena in a large-scale sodium-cooled fast reactor, the authors are developing a high-precision numerical simulation algorithm for gas-liquid two-phase flows based on a volume-of-fluid methodology. In this simulation algorithm, the PLIC (Piecewise Linear Interface Reconstruction) algorithm is employed to achieve accurate interface-tracking. Moreover, physically appropriate formulations have been conducted on gas-liquid interfaces to eliminate unphysical behaviors. Thanks to these improvements, it is confirmed that the developed simulation algorithm can reproduce the GE phenomena in a simple experiment. In this study, the simulation algorithm is applied to a real-scale GE test to check the applicability of the algorithm to the GE phenomena in the fast reactor. The mesh resolution and boundary conditions are considered carefully to be suitable for the numerical simulation of the two-phase flow around inlet and outlet pipes. As a result, transient behaviors of the vortical flows around the pipes and the accompanied GE phenomena are simulated well. In particular, the origin of the flow which induces the GE phenomena is showed clearly. Finally, from the investigation of a lot of GE phenomena observed in the simulation result, it is verified that the GE phenomena by relatively strong vortical flows are important in terms of the GE suppression in the fast reactor.