Casting and Homogenization of AlCu3.3Mg1.5Mn Alloy for Aircraft Industry

Heat treatable aluminum alloys and other alloys with similar properties are the most widely used light alloys in aeronautical construction [1-3]. These alloys have (i) high resistance to crack initiation and propagation, (ii) resistance to developing a strong lift force of the wings, (iii) high temperature, (iv)creep and fatigue vibration resistance. These age hardening Al alloys, are designed to take the mechanical stresses of the aircraft during flight. To achieve and continually improve these characteristics are necessary studies and researches on optimizing the manufacturing technological process of these types of Al alloys. This paper presents theoretical and experimental development of aluminum prealloys and high purity 2xxx Al alloys series elaboration for the aviation industry. We aimed to obtain higher energy efficiency, a better protection against gases, development of melt refining decontamination during casting. We are taking into account that the AlCu3.3Mg1.5Mn alloy has in chemical composition besides the alloying elements also a limited percentage of impurities (eg. 0.15% Si and 0.20% Fe), impurities difficult to remove from molten aluminum. In these conditions, the manufacturing processing requires some precautions such as: cleaning melting furnace and the correct choice of materials composing the charge in order to prevent contamination of the bath. The casted and homogenized Al alloys were analyzed in terms of composition and microstructure.

Shear versus vortex-induced lift force on a rigid sphere at moderate Re

The lift forces on rigid spheres entrained in a vortex and a linear shear flow are computed using a direct numerical simulation. The sphere Reynolds number is in the range 10 to 100. The lift coefficient in a vortex is shown to be nearly two orders of magnitude higher than that in a shear flow. The inviscid mechanism is shown to be inadequate to account for the enhanced lift force. The effect of free rotation of the sphere is also shown to be too small to account for the enhanced lift force. Flow structure around the sphere is studied to explain the generation of the strong lift force in a vortex.