V-ONSET: A new Penn State multiphase flow facility to probe Lagrangian interfacial transfer dynamics

For nuclear thermal hydraulics, two-phase flow with very large Reynolds number is often encountered, and as a result the flow tends to be turbulent and complex. However, our understanding of the interfacial momentum coupling between turbulent carrier phase and bubbles is very limited and often relies on empirical relationship like force laws assuming bubbles being rigid spherical particles under steady flow condition, even though the bubbles being deformable and subjected to unsteady turbulent flow constantly. To investigate fundamentals of interfacial momentum coupling between two phases, a vertical water tunnel V-ONSET (Vertical Octagonal Noncorrosive Stirred Energetic Turbulence) is designed and constructed at The Pennsylvania State University (Penn State). Since this facility is just recently completed, in this paper, we will focus on introducing this new facility along with the state-of-the-art high-speed flow visualization system and the flow measurement techniques developed in our lab that will help to identify the Lagrangian interfacial transfer dynamics. The experimental results will be used to benchmark closure models of predicative simulation for two-phase nuclear thermal hydraulics.