Study on the internal two-phase flow of the inverted-umbrella aerator

Abstract

In order to reveal the gas–liquid two-phase flow pattern of inverted-umbrella aerator, the high-speed photography technology, particle image velocimetry, and Volume of Fluid model are employed to capture the free-surface dynamics and velocity distribution. The Computational Fluid Dynamics simulations are validated by experimental data and the results are in good agreement with experiment. The simulation results of flow field, streamline distribution, velocity distribution, free-surface deformation, and turbulence kinetic energy are analyzed at in time and at radial profiles sampled at several vertical positions. Back surface of each blade revealed the area of low-pressure, which can drag air into water directly from surface and thus enhance liquid aeration and oxygenation capacity. Lifting capacity of the inverted-umbrella aerator is enough to get the liquid at the bottom of the aeration tank accelerated toward liquid surface generating the hydraulic jump. As a result, liquid phase splashes capture portions of air promoting aeration of the solution. A clear circulation whirlpool is formed during the process. The circulation whirlpool starts at the bottom of the impeller moving upward along the plate until the outer edge of the impeller, which is close to the free surface. The circulation whirlpool indicates that the inverted-umbrella aerator plays a significant role in shallow aeration. The turbulence intensity created by the impeller gradually reduces with depth. The position ( z = 0.65 H) is the watershed in the tank. The oxygen mass transfer mainly occurs in the layer above watershed.

Experimental Study of a Gas-Liquid-Solid Three-Phase Flow in an Aeration Tank Driven by an Inverted Umbrella Aerator

“…Guo [14] mainly used the PBM model to simulate the aeration process, which has high accuracy for a gas-liquid two-phase flow. Liu [15] obtained the real-time flow streamline of the inverted umbrella aerator, using a simulated gas-liquid flow.…”

“…Zhang [13] used single-factor analysis and orthogonal te the optimal working conditions of the aerator. Guo [14] mainly used simulate the aeration process, which has high accuracy for a gas-liqu Liu [15] obtained the real-time flow streamline of the inverted umbre simulated gas-liquid flow.…”

Analysis And Experimental Research on Aeration Performance of Surface Airfoil Aerator

“…The sliding grid technique was used to simulate the blade rotation, the internal calculation domain was set to rotate, the rotation speed was 30 rad / s, and the speed of the blade relative to the internal calculation domain was 0. The VOF free liquid surface model is used, and the turbulence model uses the k-ε turbulence standard model [16,17]. The k-ε turbulence model is suitable for turbulent flow at low Reynolds numbers, which can improve the accuracy and credibility of the simulation, especially the vortex Accuracy in turbulent flow [18,19] Use the patch function to set the gas-liquid distribution in the aeration tank.…”

Influence of Rotation Speed and Gas Content on the Transient Gas–Liquid Two-Phase Flow of an Electric Submersible Pump

“…The authors found that the transient Eulerian-Eulerian model is better than the VOF model in studying the gas-liquid two-phase flow and bubble dynamic behavior in the ESP. In Liang et al [12], based on computational fluid dynamics, Liang et al used high-speed camera technology and CFD modeling technology to analyze the changes in the free surface of the aeration tank and the evolution of the internal flow field and flow pattern of the inverted umbrella aerator. The high-speed photography results are consistent with the numerical simulation results, which verifies the effectiveness of the CFD model in simulating two-phase flow and lays the foundation for the selection of corresponding methods in this article.…”