Application of wire mesh sensor in analyzing gas–liquid swirling flow bubble distribution in vertical smooth tubes

Gas–liquid swirling flow is crucial for enhancing heat transfer and phase separation in industrial pipelines. This study utilizes a wire mesh sensor (WMS) to investigate bubble distribution and flow pattern evolution in vertical swirling flow within a 30 mm inner diameter smooth tube. Swirl was induced by a three-dimensional (3D)-printed helical swirler in a gas–water system, covering superficial liquid velocities jl from 0.31 to 1.10 m/s and superficial gas velocities jg from 0.04 to 0.98 m/s, encompassing bubbly to slug flow regimes. Supported by high-speed imaging, WMS provided high-resolution spatiotemporal data on void fraction, bubble size, and velocity distributions at four axial locations. Results reveal that swirl reshapes the gas–liquid interface, forming a central gas core near the swirler that decays downstream. Gas core stability and diameter depend critically on the balance between jl and jg; stable cores did not form at low velocities (jl = 0.31 m/s, jg < 0.40 m/s), while higher velocities promoted efficient phase separation. These findings advance the understanding of swirling flow dynamics, offer guidance for optimizing vortex tools by identifying stable gas core formation conditions, and validate WMS as a robust tool for detailed multiphase flow analysis.