Air entrainment in the primary impact of single drops on a free liquid surface

[摘要] Air-bubble entrainment produced by the impact of water drops on a liquid pool is investigated with the use of high-speed imaging. A wide range of drop volumes and impact velocities is considered to determine how the entrainment mechanisms change with varying the impact conditions. Five different entrainment regimes are distinguished on the basis of the observed flow phenomena. Their characteristic features are described in terms of bubble formation, crater evolution, jetting and secondary drop ejection. A regime map is reconstructed in the Froude-Weber space. Results obtained in the present study show good agreement with the phase diagrams reported in the literature and contribute to complete the scenario of the entrainment regimes. Quantitative data about the size and the residence times of the entrained nuclei are also presented.

[发布机构] DIEF- Dipartimento di Ingegneria Enzo Ferrari, Universit di Modena e Reggio Emilia, Via Vivarelli 10, Modena; 41125, Italy^1;MIMESIS Fluid Dynamics and Energy, Strada Contrada 309, Modena; 41126, Italy^2

[效力级别] 力学 [学科分类] 力学，机械学

[关键词] Drop ejection;Flow Phenomena;Free liquid surface;High speed imaging;Impact velocities;Quantitative data;Residence time;Single drops