Experimental investigation of two-phase pipe flow with ultrafast X-ray tomography and comparison with state-of-the-art CFD simulations

In this paper, we report on experimental investigations of air/water two-phase flow in a vertical pipe, which is a benchmark experiment for the development and validation of two-phase CFD models and codes. We conducted experiments for co-current upward and downward flow as well as counter-current flow at ambient temperature and pressure conditions. As measurement technique, we employed ultrafast X-ray tomography, which gives two-dimensional cross-sectional images of the gas-liquid distribution in two planes up to 2500 Hz scanning speed. In this paper, we briefly explain this technique, introduce essential data processing steps and discuss the findings of the study.