Numerical Study on Bubble-Melt Two-Phase Flows in the Production Process of Aluminum Foams

Abstract

Aluminum foams, as a representative of metallic foams, are a kind of very useful and promising functional materials. This paper reports progress in three-dimensional numerical simulations of gas bubble-metallic melt turbulent flows during the foaming process of aluminum foams, in which air is injected into molten aluminum composites and the melt is mechanical stirred by a pitched-blade impeller with an inclined shaft. The bubble-melt two phase flow in the tank is described with an Eulerian-Eulerian two fluid model, the impeller flow region is simulated based on the Multiple Reference Frames (MRF) method. Influences of gas flow rate, impeller rotation speed and initial bubble diameter on the characteristics of the liquid flow field and gas fraction distribution are examined. Computational results show that bubbles tend to accumulate behind the impeller blades and have an approximately uniform distribution near the top surface of the liquid. Gas holdup values are increased with increasing the impeller speed and gas flow rate and decreased with the bubble diameter.