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Atmospheric freezing of water droplets suspended in air followed by cloud formation and precipitation represent fundamental steps of the terrestrial water cycle. These aqueous droplets exhibit distinct freezing mechanisms and thermodynamic requirements compared to bulk water often forming metastable supercooled water at subzero temperatures on the Celsius scale (<273 K) prior to crystallization. Here, we report on a real-time spectroscopic investigation combined with simultaneous visualizations of single aqueous droplet freezing events inside a cryogenically cooled ultrasonic levitation chamber with the ultimate goal of probing the molecular structure evolution and stages of ice formation. The observed droplet freezing follows a pseudoheterogeneous ice nucleation mechanism mimicking the process that occurs for atmospherically supercooled water droplets at the air–water interface. This proof-of-concept experimental setup allows future crystallization studies of homo- and heterogeneously doped aqueous droplets under simulated atmospheric environments—also in the presence of reactive trace gases, thus untangling dynamic molecular interactions and chemical reactions, which are of fundamental interest to low-temperature atmospheric chemistry delineating with ice nucleation mechanisms.
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This content will become publicly available on July 27, 2026
Dynamics of Supercooled Water Droplet Upon Impacting on Surface Dielectric Barrier Discharge Plasma
Abstract Aircraft icing, resulting from the freezing of supercooled water droplets on exposed surfaces, presents considerable hazards to flight safety by impairing aerodynamic performance and operating efficiency. This study empirically examines the interaction dynamics of supercooled water droplets and dielectric barrier discharge (DBD) plasma actuators, emphasizing electrical, thermal, and phase transition phenomena. Supercooled droplets were produced via sonic levitation in a freezer set at −10°C and subsequently deposited onto the plasma actuator surface at −5°C. Electrical diagnostics indicated a reduction in current intensity following droplet impact which inhibited plasma discharge activity. Thermal imaging detected localized heating at nucleation locations, indicating a temperature plateau during freezing caused by latent heat release. A study of spatial temperature along the droplet x-axis revealed a pronounced thermal gradient, with the most significant temperature rise occurring adjacent to the plasma-exposed area. High-speed imaging elucidated droplet dynamics, demonstrating spreading, descent towards the ground electrode, and subsequent retraction following stabilization. These discoveries improve the comprehension of plasma-droplet interactions, aiding in the improvement of plasma-based anti-icing technology. This research promotes the creation of effective and environmentally friendly solutions for aviation safety and other areas affected by icing hazards.
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- Award ID(s):
- 2242311
- PAR ID:
- 10639094
- Publisher / Repository:
- American Society of Mechanical Engineers
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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