Jet-stirred homogeneous isotropic turbulent water tank for bubble and droplet fragmentation.

Abstract

We present a new jet-stirred turbulent water tank designed to produce homogeneous isotropic turbulence, focusing on multiphase flow phenomena. In particular, the facility features a high Taylor-microscale Reynolds number of O(103) that can ensure a large inertial range and is suitable for studying the breakage of droplets and bubbles in line with the Kolmogorov-Hinze theory. The turbulence is created in an octagonal horizontal water tank by two opposing jet arrays, where each jet can release continuous flow with adjustable velocity. The acrylic section design allows optical access for six high-speed cameras to apply time-resolved visualization techniques. Using 3D Lagrangian particle tracking, we provide a complete statistical characterization of the turbulence field: our measurements reveal a maximum turbulence anisotropy of 10% in the center of the water tank with an energy dissipation rate up to ɛ = 0.3 m2 s-3. This high energy dissipation rate is sufficient to trigger the breakage of bubbles and droplets of O(1-10 mm), which falls in the turbulence inertial range. Furthermore, we demonstrate the capability of our imaging system and reconstruction methods for multiphase flow studies with examples of full 3D topology reconstruction coupled with surrounding flow measurements.