TY - JOUR

T1 - Interaction of impacting water drop with a heated surface and breakup into microdrops

AU - Gatapova, Elizaveta Ya

AU - Kirichenko, Ekaterina O.

AU - Bai, Bofeng

AU - Kabov, Oleg A.

N1 - Publisher Copyright: © 2018 by Begell House.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - Drop impact is important for numerous industrial processes. The recent progress in investigations of drop impact on heated solid surface covers the processes near and above the boiling temperature of the liquid. There is a gap in understanding of drop dynamics for the substrate temperature below the liquid boiling point. We conduct a detailed study of the interaction of the water drop of 10µl impacting on a heated sapphire plate with a temperature varied within a range of 23–135◦C. Characteristic stages of drop interaction with a substrate at various temperatures are identified, namely impact, spreading, rollback, one liquid column splashing, microdrops detachment, formation, stabilization, breakup, boiling, and evaporation. We show that the spreading time and maximal spreading diameter of the droplet are dominated by inertia and practically independent of the temperature. The influence of the temperature on viscosity dissipation, which limits the maximum spreading diameter, is not significant. However, the temperature rise leads to a considerable decrease of the liquid column contact diameter and to an increase of the liquid column height at the splashing stage. It is revealed that the contact line velocity at the rollback stage depends on temperature. Microdrop detachment from the liquid column is observed for a substrate temperature of 60–100◦C. Beginning from the substrate temperature of 100◦C, the liquid column height is decreased again. The most important observation is the drop breakup into several sessile microdrops just after the spreading for 135◦C, which prevents the rollback and rebound. We show the possible importance of the Marangoni force for thin liquid film breakup and detect the presence of microbubbles, which is also potentially important for breakup.

AB - Drop impact is important for numerous industrial processes. The recent progress in investigations of drop impact on heated solid surface covers the processes near and above the boiling temperature of the liquid. There is a gap in understanding of drop dynamics for the substrate temperature below the liquid boiling point. We conduct a detailed study of the interaction of the water drop of 10µl impacting on a heated sapphire plate with a temperature varied within a range of 23–135◦C. Characteristic stages of drop interaction with a substrate at various temperatures are identified, namely impact, spreading, rollback, one liquid column splashing, microdrops detachment, formation, stabilization, breakup, boiling, and evaporation. We show that the spreading time and maximal spreading diameter of the droplet are dominated by inertia and practically independent of the temperature. The influence of the temperature on viscosity dissipation, which limits the maximum spreading diameter, is not significant. However, the temperature rise leads to a considerable decrease of the liquid column contact diameter and to an increase of the liquid column height at the splashing stage. It is revealed that the contact line velocity at the rollback stage depends on temperature. Microdrop detachment from the liquid column is observed for a substrate temperature of 60–100◦C. Beginning from the substrate temperature of 100◦C, the liquid column height is decreased again. The most important observation is the drop breakup into several sessile microdrops just after the spreading for 135◦C, which prevents the rollback and rebound. We show the possible importance of the Marangoni force for thin liquid film breakup and detect the presence of microbubbles, which is also potentially important for breakup.

KW - Drop impact

KW - Drop spreading

KW - Heating

KW - High-speed imaging

KW - Marangoni

KW - Microbubbles

KW - Rupture

KW - Secondary droplets

KW - Spray cooling

KW - Surface tension

KW - FILM

KW - high-speed imaging

KW - surface tension

KW - FLOW

KW - rupture

KW - secondary droplets

KW - microbubbles

KW - drop impact

KW - drop spreading

KW - DYNAMICS

KW - spray cooling

KW - heating

UR - http://www.scopus.com/inward/record.url?scp=85054018627&partnerID=8YFLogxK

U2 - 10.1615/InterfacPhenomHeatTransfer.2018026089

DO - 10.1615/InterfacPhenomHeatTransfer.2018026089

M3 - Article

AN - SCOPUS:85054018627

VL - 6

SP - 75

EP - 88

JO - Interfacial Phenomena and Heat Transfer

JF - Interfacial Phenomena and Heat Transfer

SN - 2169-2785

IS - 1

ER -