Multiphase flow in small-gap geometry: A combined numerical and experimental study

Abstract A joint experimental and simulation study of a gas-liquid flow with non-quiescent liquid is presented, in the case of a small-gap geometry, such as the ones implemented in nuclear fuel recycling processes to mitigate criticality issues. The numerical model is based on a Euler-Euler approach that has been selected and tested on existing data published by Krepper et al. (2007) for the bubbly flow of air in a flat rectangular column filled with quiescent water. Thanks to the complementary experimental study implementing full-scale and non-intrusive velocimetry and granulometry measurements, the effects of the liquid flow rate and of the bubbles polydispersity have been investigated and the corresponding model's predictions validated based on velocity measurements. These new results highlight that, although the flow field deviates strongly from the one encountered in the typical configurations investigated so far ( i.e. cylindrical or rectangular bubbly flows columns involving bubbles injection at the bottom of a quiescent liquid), in this case also, the bubble size distribution plays a major role in the two-phase flow features and that a proper description of it is needed.