Simulation of aluminum foam formation and distribution uniformity

Effects of bubble size formed on orifice inside an aluminum melt and bubble distribution on a foaming chamber surface were studied by experimental simulation. The bubble size formed on the liquid surface is increased with the increase in air flow rate and pressure, orifice size, and immersion depth. The orifice with 45° taper head produces smaller bubbles than that with 60° taper and flat ones. A calculation formula is established to predict bubble size formed on the orifice inside a quiescent liquid at a given surface bubble size, and the calculation agrees well with the measurement data. Orifice reciprocal agitation improves cell size uniformity of the closed-cell aluminum foam, compared with orifice rotating. Although orifice rotating is effective in producing smaller bubbles, the agitation of orifice reciprocating produces more uniform bubble distribution on the liquid surface. The bubble distribution is further improved when evenly spaced orifices are replaced by nonequidistant orifices.