It is essential to comprehend the gas–liquid two-phase flow in packed beds across various fields, including evaluating the stability of unsaturated soil with air–water flow in soil pores and assessing the impact of CO2 leakage incidents in subsea carbon capture and storage systems. Recently, wire-mesh sensors (WMSs) have been employed to measure gas–liquid two-phase flow in packed beds. However, the relationship between the instantaneous void fraction acquired by WMSs and the actual two-phase flow has not been sufficiently explored. This study presents a comparison between WMSs and visualization using refractive index matching for measuring two-phase flow in packed beds, aiming to assess the applicability of WMS to packed beds. Air–water two-phase flow experiments were conducted across a range of gas (13.3–1066.7 mm/s) and liquid (0–16.7 mm/s) superficial velocities. WMS was used to quantify the instantaneous void fraction, while visualization provided direct observation of gas–liquid interactions. It was confirmed that WMS properly detected bubbles passing through the wire electrodes, but it also detected bubbles passing near the cross points of the electrodes.
Ueda et al. (Wed,) studied this question.