ID 82

Post-impact spreading of hydrocarbon fuel drops impacting on a solid surface

 

Abstract:

The impact process of hydrocarbon fuel drops under ambient temperature conditions exhibits no receding, however undergoes post-impact spreading after reaching the maximum spreading diameter in the inertia-driven spreading regime. The difference between the maximum spreading diameter measured at the end of inertia-driven spreading phase and final diameter measured at an instant far away from the start of impact is not well documented in previous studies. The present study analyzes the inertia-driven maximum spreading and the post-impact final spreading of impacting fuel drops on a smooth solid surface under ambient atmospheric temperature condition. Four hydrocarbon fuels, n-heptane, n-decane, Jet A-1 and Diesel, are considered in the study. The experiments of drop impact are conducted at varying Weber number in the range 27 – 914. The temporal variation of impacting drop parameters are deduced from high speed videos of drop impact dynamics captured during experiments. The experimental measurements of maximum spreading diameter are verified with the support of existing theoretical models as well as previously reported experimental data on fuel drop impacts. The measured final spreading diameter is always higher than the maximum spreading diameter and the variation of the difference between the two parameters with Weber number is described for different fuels. A systematic analysis of spreading dynamics beyond the inertia-driven maximum spreading is carried out. The results arrived from the analysis are useful to distinguish the post-impact spreading of impacting drops with the static spreading (with no impact velocity) of fuel drops.