PIV VELOCITY MEASUREMENTS IN THE WAKE OF AN OBSTRUCTION SIMULATING A TAYLOR BUBBLE IN A DUCT

摘要

Mean velocity measurements in the wake of an obstruction simulating a Taylor bubble (or slug) have been obtained using Particle Image Velocimetry (PIV) in a duct. Two flow rates were established: one represented the flow behind a large gas slug rising in quiescent fluid and the other represented an idealized slug rising with a higher relative velocity, as typically found in higher void fraction churn-turbulent flow. The results indicate that, in a reference frame fixed to the slug, the flow around the sides of the slug behaves like wall bounded jets which eventually merge downstream of the slug. The ratio of wake volume to slug volume is nearly the same for both Reynolds numbers tested (i.e., 3.0 at Re=3,628 and 2.9 at Re=7,257) although the measurements suggest that the wake size decreases somewhat as the Reynolds number is increased.