Numerical Simulation Of Two Phase Turbulent Flow With Aluminium Foam Processing

Metal foam is a promising functional and structural material, and has outstanding thermal,mechanical, acoustical, electromagnetic shielding performances, and recycle features, which hasbeen used widely in the fields of automobile, spaceflight, architectural industry, shipbuildingindustry, mechanical and electronic manufacture and biomedicine. Among technologies, the gasjetting on preparation for metal foam has become one of advanced processing technology withthe special advantages of simple equipment, low cost and scale production. Especially,aluminum and metal foam of aluminum alloy have been a hotspot of research. The technologyof preparation for alloy aluminum foam has become the focus of materials science research inthe21st century. In the process of preparation for aluminum foam, a core issue is how to controldistribution uniformity of bubble. Under the formation, movement and dispersion of bubbles,there are lots of factors in the distribution uniformity of bubble. The traditional and empiricalmethod is small-scale, high cost, long cycle, and heavy workload, which is hard to know theeffect of various operating parameters in the preparation process, as well as to understand themechanism and the relevant laws. Numerical simulation technology is an effective design tool,which is easy to use and versatile, to reveal the physical mechanism depth, analysis andoptimize various factors in the short time.In this paper, numerical simulation of liquid aluminum-bubble two-phase turbulentflow in the process of gas jetting on preparation for metal foam was presented by usingEuler-Lagrange model, mainly including two aspects, gassing from a single hole at thebottom center and from multi-holes. For which, the motion characteristics of the bubbleduring the process of metal foam was revealed, and providing a theoretical basis and thecorresponding prediction model for the preparation and optimization of aluminum foam.The simulation results of gassing from a single hole is, after gas enter the bath, moltenaluminum and bubble interacted and rose along the central axis, and downward at the near-wall,making the liquid recirculation within the molten pool. Under the same gas flow rate, axialvelocity of the aluminum liquid was increased along the radial direction; the turbulent kineticenergy and turbulent kinetic energy dissipation rate was reached a plateau near the vent anddecreased along the pool height; the unevenness of bubble concentration was fastened between0.35and0.55at four different gas flow rate. When the gas flow rate was1.0L/min, theconcentration unevenness was smallest, which is beneficial to the collection of the bubble. Fromthe results of gassing from multi-holes, it could be seen that the distribution of bubbles in the exit was related with the jetting velocity, the angle θ and φ. With the increase of angle θ,the distribution of bubbles in the exit became uneven at the certain values of the jetting velocityand the angleφ; when the jetting velocity increased, the distribution of bubbles also becameuneven at the same values of the angle θ and φ; As the jetting velocity is10m/s, and theangle θand φ is30degree, the distribution of bubbles in the exit was the most uniform,which is helpful to make higher density rank of manufactured foam.