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Examen de la mobilité des gouttelettes et de la vitesse critique de l’air sur des surfaces poreuses imprégnées de liquide et glissantes avec un gradient linéaire de mouillabilité.

Examination of droplet mobility and critical air velocity on slippery liquid-infused porous surfaces with a linear wettability gradient.

Numéro : 2211

Auteurs : FREEMAN S. R., SOMMERS A. D.

Résumé

In this work, slippery liquid infused porous surfaces (SLIPS) are used in combination with a linear wettability gradient to influence the mobility of water droplets on surfaces ranging in size from 5-50 μL. The overall aim is to study the effects of surface wettability and micro-structural roughness on the water drainage characteristics of functionalized aluminum surfaces.
The primary focus is on comparing the critical air velocities of water droplets on aluminum surfaces containing laser-etched microchannels coated with various KrytoxTM GPL series oils. The microchannel design is used to establish a linear wettability gradient on the surface through roughness. Four different KrytoxTM oils were studied of varying viscosity and fluorination level (i.e. GPL 102, GPL 103, GPL 104, and GPL 106). The surfaces were then placed in a subsonic wind tunnel and tested to measure the critical air speed needed for the onset of droplet motion. The critical air speed was fully characterized for the GPL 103, 104, and 106 coated surfaces. On the GPL 103 treated surface, the average critical velocity for the movement of 5 μL droplets was the lowest (only 7.3 m/s), while the critical air speed on the GPL 104 and 106 treated surfaces averaged 8.2 m/s and 9.3 m/s, respectively. Wind tunnel tests for the SLIPS sample with the GPL 102 coating were inconclusive due to oil displacement caused by the air shear force generated during testing. Although the critical air speed was not determined, spontaneous droplet motion on the GPL 102 coated surface was still observed in the absence of air flow. Spontaneous translational droplet motion was also observed on the surface coated with the GPL 103 KrytoxTM oil too. Analysis of the spontaneous droplet motion was then performed to determine the maximum travel distance and instantaneous speed of the moving droplets. In addition to wind tunnel testing, each surface was also characterized using a goniometer to determine its static contact angle and contact angle (CA) hysteresis. The CA hysteresis, which is typically a good predictor of droplet mobility on a surface, was found by measuring the advancing and receding contacts angles on a surface. To date, our data have shown that a carefully selected SLIPS oil (such as KrytoxTM GPL 103 or 104) has the potential to help with droplet mobility and drainage; however, additional testing is warranted to explore other gradient surface designs and to measure the long-term durability of these surfaces.

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Pages : 9 p.

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Détails

  • Titre original : Examination of droplet mobility and critical air velocity on slippery liquid-infused porous surfaces with a linear wettability gradient.
  • Identifiant de la fiche : 30033085
  • Langues : Anglais
  • Sujet : Technologie
  • Source : 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Date d'édition : 17/07/2024

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