关键词: 泡沫铝, 多重参考系, 气液两相流, 气含率

Abstract: The production process of aluminum foams by air injecting into molten aluminum composites is a highly complex two-phase flow with mechanical stirring. This work presents the results in Computational Fluid Dynamics simulations of gas-liquid turbulent flows induced by a pitched-blade turbine (four blades, 45 inclined) with a inclined shaft. A two fluid model incorporated with the Multi-reference Frame (MRF) method is used to predict the three-dimensional two-phase flow in the foaming tank. Bubble size distribution is also predicted by solving a transport equation for the bubble number density function, which accounts for break-up and coalescence phenomena. Furthermore, the averaged total and local gas fractions and bubble diameters are predicted by means of volume integration. The influences of impeller rotational speed and gas flowrate on bubble diameter and distribution are examined. Computational results show that gas volumetric fraction increases with increasing gas flowrate and impeller speed, bubble size increases with increasing gas flowrate and decreasing impeller speed.

Key words: aluminum foam, multi-reference frame, gas-liquid flow, gas volumetric fraction