Numerical simulation on melt flow with bubble stirring and temperature field in aluminum holding furnace

Abstract

The numerical model for predicting the flow and temperature fields of the melt in holding furnace with porous brick purging system were set up using Euler-Lagrange approach. In this model, bubbles coalescence and disintegration were ignored based on the dimensionless analysis, and the bubble size was assumed to be obedient to Rosin-Rammler distribution with a mean size of 0.6 mm. The results show that on reference operating condition, during the heating and agitation process, melt mixes well in the furnace, and the melt velocity increases with the increase of gas flux. Holding the melt for 30 min causes the max temperature in the bulk melt to increase to 60 K. After holding the heat, the agitation processing restarts, and it takes 10 min for the stratified melt to retrieve the homogeneous temperature field when the gas flux is 10 L/min, which shows deficient alloying and degassing in the melt. With the increase of gas flux from 10 to 20, 30 and 40 L/min, the necessary recovery time decreases from 10 to 6, 5 and 4 min gradually, which shows the improvement of the stirring efficiency. Depending on the processing purposes, for both good degassing performance and gas saving, proper operating strategy and parameters (gas flux, primarily) could be adjusted.

Keywords

aluminum holding furnace / porous brick / bubble agitation / computational fluid dynamic method

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