Experimental and Computational Investigation of Two Phase Gas−liquid Flows: Point Source Injection at the Center

Abstract

In this work, an experimental and numerical investigation of hydrodynamics in a liquid induced by a bubble plume is carried out. The gas is introduced through a needle in the center of the tank containing water. The gas−liquid flow in such systems is inherently unsteady. Particle image velocimetry (PIV) was used to experimentally determine the transient velocity fields in the system. For this gas−liquid flow system, both the fluctuating and mean liquid velocities were determined experimentally by 2D and 3D PIV. The system was investigated for a liquid phase Reynolds number in the range of 3.7 × 104 to 1.8 × 105 and bubble phase Reynolds number in the range from 2350 to 11 773. The behavior of the system was simulated in FLUENT 6.3.26 using a two fluid Euler−Lagrangian (EL) model with a constant bubble size of 5 mm. Here, water is treated as the continuous phase, and gas bubbles are treated as the dispersed phase. Motion of the bubbles renders the flow turbulent, and this effect is captured by the standard k−ε turbulence model. The temporal prediction of the flow field is compared with experimental results obtained from 2D and 3D measurements. The predictions from the 3D simulations capture the oscillating behavior found using 3D PIV. The 2D simulations predict a significantly higher value of turbulent viscosity. This is hypothesized as the reason as to why these simulations do not capture the oscillating behavior.