Thermally induced secondary drop atomisation by single drop impact onto heated surfaces

The paper reports an experimental study of single millimetric water drop impacts onto a hot aluminium alloy (AlMg₃) surface. The main aim of this investigation was to evidence the effect of the heat transfer mechanism on the secondary atomisation, but the effect of impact velocity and surface characteristics on the impact outcomes were also studied. Two non-intrusive measurement techniques, namely Phase Doppler Anemometer and image analysis, were used to describe the time evolution of the secondary droplet diameters and to study the effect of surface temperature, surface roughness and impact velocity on the impact outcomes. The morphology of drop impact is described for two different boiling regimes and quantitative results about the arithmetic mean and Sauter mean diameters of the secondary droplets are reported. An attempt to correlate the Sauter mean diameter of secondary drops with the nominal surface temperature is also reported.