Heat Flux Density Evaluation in the Region of Contact Line of Drop on a Sapphire Surface Using Infrared Thermography Measurements

Evaporating water drops on a horizontal heated substrate were investigated experimentally. The heater was made of a constantan foil with the thickness of 25 μm and size of 42 × 35 mm2. The temperature of the bottom foil surface was measured by the infrared (IR) camera. To determine the heat flux density during evaporation of liquid near the contact line, the Cauchy problem for the heat equation was solved using the temperature data. The maximum heat flux density is obtained in the contact line region and exceeds the average heat flux density from the entire foil surface by the factor of 5–7. The average heat flux density in the region wetted by the drop exceeds the average heat flux density from the entire foil surface by the factor of 3–5. This fact is explained by the heat influx from the foil periphery to the drop due to the relatively high heat conductivity coefficient of the foil material and high evaporation rate in the contact line region. Heat flux density profiles for pairs of sessile droplets are also investigated.

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Heat flux density in the region of droplet contact line on a horizontal surface of a thin heated foil

Thermophysics and Aeromechanics ◽

10.1134/s086986431705016x ◽

2017 ◽

Vol 24 (5) ◽

pp. 803-806 ◽

Cited By ~ 5

Author(s):

V. V. Cheverda ◽

A. L. Karchevsky ◽

I. V. Marchuk ◽

O. A. Kabov

Keyword(s):

Heat Flux ◽

Flux Density ◽

Contact Line ◽

Heat Flux Density ◽

Horizontal Surface

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HEAT FLUX DENSITY MEASURMENTS IN THE CONTACT LINE OF THE HEATED SESSILE DROPLET/FALLING DOWN LIQUID RIVULET

10.1615/ihtc16.mpf.024707 ◽

2018 ◽

Cited By ~ 1

Author(s):

Vechaslav V. Cheverda ◽

T. G. Ponomarenko ◽

Andrey L. Karchevsky ◽

Oleg A. Kabov

Keyword(s):

Heat Flux ◽

Flux Density ◽

Contact Line ◽

Heat Flux Density ◽

Sessile Droplet

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THERMAL BEHAVIOR AND IGNITION OF HIGH-ENERGY MATERIALS CONTAINING B, ALB2, AND TIB2

NONEQUILIBRIUM PROCESSES. Vol. 2. Fundamentals of combustion ◽

10.30826/nepcap2018-2-14 ◽

2020 ◽

Author(s):

A. G. Korotkikh ◽

◽

V. A. Arkhipov ◽

I. V. Sorokin ◽

E. A. Selikhova ◽

...

Keyword(s):

Heat Flux ◽

Thermal Behavior ◽

Flux Density ◽

Ignition Delay ◽

Delay Time ◽

Heat Flux Density ◽

Ignition Delay Time ◽

High Energy ◽

Energy Materials ◽

High Energy Materials

The paper presents the results of ignition and thermal behavior for samples of high-energy materials (HEM) based on ammonium perchlorate (AP) and ammonium nitrate (AN), active binder and powders of Al, B, AlB2, and TiB2. A CO2 laser with a heat flux density range of 90-200 W/cm2 was used for studies of ignition. The activation energy and characteristics of ignition for the HEM samples were determined. Also, the ignition delay time and the surface temperature of the reaction layer during the heating and ignition for the HEM samples were determined. It was found that the complete replacement of micron-sized aluminum powder by amorphous boron in a HEM sample leads to a considerable decrease in the ignition delay time by a factor of 2.2-2.8 at the same heat flux density due to high chemical activity and the difference in the oxidation mechanisms of boron particles. The use of aluminum diboride in a HEM sample allows one to reduce the ignition delay time of a HEM sample by a factor of 1.7-2.2. The quasi-stationary ignition temperature is the same for the AlB2-based and AlB12-based HEM samples.

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