TY - JOUR

T1 - Visualization of drop and bubble dynamics om heated sapphire plate by high-speed camera enhanced by stereomicroscope

AU - Gatapova, Elizaveta Ya

AU - Sitnikov, Vadim O.

AU - Sharaborin, Dmitriy K.

N1 - Funding Information: This research was financially supported by the Russian Science Foundation (Project No. 20-19-00722). The calibration of thermocouples and high-speed camera installation were carried out under state contract with IT SB RAS (121031800213-0 for E.G.; 121031100246-5 for D.S.). Publisher Copyright: © 2022 by Begell House, Inc. www.begellhouse.com.

PY - 2022

Y1 - 2022

N2 - The boiling process is one of the most effective ways for heat transfer enhancement. During the spray cooling and drop impingement to a hot surface, the incipient bubbles grow and coalescence inside a thin liquid film. This paper presents high-speed top-view visualization together with a stereomi-croscope of drop dynamics and evolution of bubbles formed inside the water drop impacted to the substrate with a temperature varied from 90 to 150◦C. The nucleate and transition boiling regimes are considered. Stereomicroscope has a large depth of field, allowing capturing many features of the interaction of bubbles and their dynamics in a thin layer of liquid. Top-view visualization made it possible to estimate the bubble size and diameter, and accurately determine the cause and time of rupture of the liquid film. Histograms of bubble sizes were plotted using data over the entire area of the thin liquid film at different time points. The average diameter of the bubbles is shown to increase over time up to 160–200µm at the moment of liquid droplet breaks. This value is found to be inde-pendent on the substrate temperature, while the growth rate of bubbles in a liquid droplet strongly depends on the heat flux. The maximum and minimum contact diameters of the droplet decrease with increasing substrate temperature.

AB - The boiling process is one of the most effective ways for heat transfer enhancement. During the spray cooling and drop impingement to a hot surface, the incipient bubbles grow and coalescence inside a thin liquid film. This paper presents high-speed top-view visualization together with a stereomi-croscope of drop dynamics and evolution of bubbles formed inside the water drop impacted to the substrate with a temperature varied from 90 to 150◦C. The nucleate and transition boiling regimes are considered. Stereomicroscope has a large depth of field, allowing capturing many features of the interaction of bubbles and their dynamics in a thin layer of liquid. Top-view visualization made it possible to estimate the bubble size and diameter, and accurately determine the cause and time of rupture of the liquid film. Histograms of bubble sizes were plotted using data over the entire area of the thin liquid film at different time points. The average diameter of the bubbles is shown to increase over time up to 160–200µm at the moment of liquid droplet breaks. This value is found to be inde-pendent on the substrate temperature, while the growth rate of bubbles in a liquid droplet strongly depends on the heat flux. The maximum and minimum contact diameters of the droplet decrease with increasing substrate temperature.

KW - bubble growth

KW - bubble interactions

KW - drop impact

KW - high-speed

KW - hot surface

KW - sapphire plate

UR - http://www.scopus.com/inward/record.url?scp=85134237988&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/89cd2d67-4fd8-3128-85ab-8b4b6dae4f6f/

U2 - 10.1615/JFlowVisImageProc.2022042253

DO - 10.1615/JFlowVisImageProc.2022042253

M3 - Article

AN - SCOPUS:85134237988

VL - 29

SP - 87

EP - 103

JO - Journal of Flow Visualization and Image Processing

JF - Journal of Flow Visualization and Image Processing

SN - 1065-3090

IS - 2

ER -