Numerical Simulation And Experimental Research Of Molten Aluminum Alloy Through Ceramic Foam Filters By Centrifugal Filtration Process

Aluminum alloy,which with a series of better properties than other nonferrous materials,has been wildly used in automobile,power,national defense and other industries as a nonferrous structure material.But due to the existence of metallurgical defects,such as gas and inclusions,it will cause great damage to the mechanical properties and performance of aluminum alloy products.In order to manufacture higher quality products and improve their comprehensive performance,It's necessary to remove impurity from molten aluminum alloy.Filtration technology as the most simple,cheapest and effective method to remove nonmetallic inclusions in molten metal has been proved.Ceramic foam filters has been used in the filtration system because of its excellent ability of reducing the inclusions.When using the large pore density ceramic foam filters to improve the filtration efficiency,the molten metal will under higher resistance,leads to the molten metal cannot penetrate the filters.Therefore,the centrifugal field is introduced based on ceramic foam filtration,which can increase pressure on the molten metal and make it penetrate the smaller pore diameter of ceramic foam filters,so as to improve the filtration effect.In this paper,numerical simulation and experimental research of molten aluminum alloy through ceramic foam filters by centrifugal filtration process has been carried out,gained further insight into the flow and heat transfer process of molten aluminum alloy in the ceramic foam filters,meanwhile studied the mechanism and efficiency of ceramic foam filters filter out inclusions.The key step of numerical simulation is reconstruct the representative element volume(REV)of ceramic foam pore structure.The pore structure parameters of ceramic foam were obtained by scanning electron microscope,and based on the Weaire-Phelan foam model,constructed two idealized REV of ceramic foam with different porosity ranges,ultimately studied the flowing behavior of molten aluminum alloy and trajectory of inclusions by using the ANSYS-FLUENT software.The effects of the filtration process parameters and the structural parameters of ceramic foam,such as the temperature of molten aluminum alloy,rotational speed of filtration device,porosity and pore density of ceramic foam on the trajectory of inclusions and the distribution of flow field and temperature field are studied in pore scale simulation.The pore scale simulation results are as follows:(1)Pore density of ceramic foam,rotational speed of filtration device and the temperature of molten aluminum alloy are positively correlated with the filtration efficiency of ceramic foam,porosity of ceramic foam is negatively correlated with the filtration efficiency.(2)Pore density of ceramic foam and rotational speed of filtration device are positively correlated with the flow resistance of molten aluminum alloy in ceramic foam,the temperature of molten aluminum alloy and porosity of foam ceramics are negatively correlated with the flow resistance.(3)The order of various key factor's effect on the filtration efficiency and the flow resistance is as follows :pore density of ceramic foam> rotational speed of filtration device>the temperature of molten aluminum alloy>porosity of ceramic foam.Finally,the numerical simulation results are compared with the experimental results of ceramic foam centrifugal filter molten aluminum alloy,find out that they are basically agreed well,Therefore,the results of numerical simulation have theoretical significance value to optimize the filtration process of the ceramic foam centrifugal filter molten aluminum alloy.In order to improve the filtration efficiency,the ceramic foam with high porosity and low porosity can be selected,and the temperature of the molten aluminum alloy and the rotational speed of filtration device can be increased appropriately.