Drop array impacts on heated surfaces: secondary atomization characteristics

The paper reports on experimental investigation of multiple drop impacts on heated surfaces. A line array madeby three drops of millimetric size impacts on high effusivity surfaces at moderate Weber numbers (110-660) anddifferent surface temperatures to encompass various boiling regimes. A CCD camera and a Phase DopplerAnemometer were used to measure the size of the secondary droplets formed after impact, in a range from 5.5 mmto few mm. The effect of adjacent drop interaction was studied by comparison with single drop impact under thesame experimental conditions. The effect of drop spacing was studied by varying the array configuration. Theeffect of surface roughness is also addressed. Quantitative results are reported together with a qualitative analysisof the impact morphology. A strong effect of the surface temperature on the mean drop size was observed andrelated to the boiling regimes. The drop spacing was found to influence the drop size of secondary droplets, but theeffect is strongly related to the impact velocity.