Experimental methodology and procedure for SAPPHIRE: a Semi-automatic APParatus for High-voltage Ice nucleation REsearch
<p>Ice nucleation is of great interest for various processes such as cloud formation in the scope of atmospheric physics, and icing of airplanes, ships, or structures. Ice nucleation research aims to improve the knowledge about the physical mechanisms and to ensure the safety and reliability...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-01-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/14/223/2021/amt-14-223-2021.pdf |
| Summary: | <p>Ice nucleation is of great interest for various processes such as cloud formation in the scope of
atmospheric physics, and icing of airplanes, ships, or structures. Ice nucleation research aims to
improve the knowledge about the physical mechanisms and to ensure the safety and reliability of
the respective applications. Several influencing factors like liquid supercooling or
contamination with nucleants, as well as external disturbances such as an electric field or
surface defects, affect ice nucleation. Especially for ice crystal formation in clouds and icing of
high-voltage equipment, an external electric field may also have a strong impact on ice
nucleation. Although ice nucleation has been widely investigated for numerous conditions, the
effect of an electric field on ice nucleation is not yet completely understood; results reported
in literature are even contradictory on some issues.</p>
<p>In the present study, an advanced experimental approach for the examination of ice nucleation in
water droplets exposed to an electric field is described. It comprises a method for droplet
ensemble preparation and an experimental setup, which allows observation of the droplet ensemble
during its exposure to well-defined thermal and electric fields, which are both variable over a
wide range. The entire approach aims at maximizing the accuracy and repeatability of the
experiments in order to enable examination of even the most minor influences on ice nucleation.
For that purpose, the boundary conditions the droplet sample is exposed to during the experiment
are examined in particular detail using experimental and numerical methods. The methodological
capabilities and accuracy have been demonstrated based on several ice nucleation experiments
without an electric field, indicating almost perfect repeatability.</p> |
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| ISSN: | 1867-1381 1867-8548 |