HEAT-FLOW IN SPRAY-FORMED AL-4CU

This paper describes a direct comparison of computer modelling predictions and experimental measurements of the spray dynamics, spray cooling and billet heat flow during spray forming of an Al-4 wt.%Cu alloy. The axial gas flow pattern is measured by phase Doppler anemometry, and the results are used in a numerical model to predict the velocities of a range of different sized Al-4wt.%Cu droplets in the spray which are in reasonable agreement with Al-4wt.%Cu droplet velocities measured by phase Doppler anemometry. The spray solid fraction is then calculated by integration of individual droplet solid fractions over a measured droplet size distribution, and used in a numerical model of heat flow in the spray-formed billet. The resulting predictions are again in reasonable agreement with Al-4wt.%Cu billet top surface temperatures measured by infrared thermal imaging during spray forming.