Numerical simulation of a stirring purifying technology for aluminum melt

Compared to the traditional Star impeller, the designed impeller (hereinafter termed as the XSR impeller) has the characteristic of pumping which can promote degassing efficiency, and smaller area of the dead region and higher turbulent kinetic energy are obtained within the melt simultaneously. In the range of the discussed immersion depths of impeller (H = 185 mm, 315 mm and 435 mm), both too shallow depth (185 mm) and too deep depth (435 mm) are bad for the distribution of flow field. For the discussed rotational velocities of impeller (V = 390 rpm, 430 rpm, 480 rpm and 550 rpm), as the V increases, the intensity of fluid flow increases accordingly, and the area of lower turbulent kinetic energy reduces gradually. For the XSR impeller, the optimal immersion depth and rotational velocity are 315 mm and 550 rpm, respectively. The experimental data are in well accordance with the simulated results. Under the optimal process parameters, the average volume fraction of voids and inclusions of the A356 melt decreases by 98%. The as-cast A356 alloy with higher cleanliness exhibits an ultimate tensile strength (UTS) of 161 MPa, a yield strength (YS) of 72 MPa and an elongation (EL) of 14%.