Three-component turbulent velocity fields in the liquid phase of air-water horizontal intermittent pipe flows

The present work describes an experimental study of a horizontal, gas-liquid pipe flow in the intermittent regime. Event-triggered, high-speed stereoscopic particle image velocimetry (SPIV) combined with laser-induced fluo-rescence (LIF) were used to measure all three components of the velocity vector at different pipe cross-sections, referred to the elongated bubble nose tip. A 40-mm inner diameter pipe was used as test section, while water and air with superficial velocities of jL = 0.3, 0.4 and 0.5 m/s, and jG = 0.5 m/s formed the intermittent flow pattern. A set of photogate sensors was used to measure the two-phase flow statistics, and to trigger the SPIV system, allowing for the determination of ensemble-averaged, three-component velocity fields of the turbulent liquid flow in cross-stream planes around the elongated gas bubble. The original data obtained revealed the influence of the faster-moving gas bubbles on the dynamics of the liquid velocity field, providing valuable information for a better understanding of the physics governing the flow, and for validation of numerical models. The velocity measurements near the pipe bottom wall allowed the determination of the wall shear stress in the liquid plug region.