Nonisothermal drop impact and evaporation on polymer nanofiber mats

Weickgenannt, Christina M.; Zhang, Yiyun; Lembach, Andreas; Roisman, Ilia V.; Gambaryan‐Roisman, Tatiana; Yarin, Alexander L.

doi:10.1103/physreve.83.036305

Cited by 59 publications

(45 citation statements)

References 21 publications

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“…However, they may not really behave exactly like lotus leaves when dynamic water droplets impact them. Therefore, the impingement of water droplet has also been investigated to characterize the wettability of superhydrophobic coatings under dynamic conditions [125]. Currently, bouncing dynamics of impact droplets on solid surfaces intensively appeal to researchers due to its importance in many industrial fields, including anti-icing, dropwise condensation, and self-cleaning.…”

Section: Dynamic Water Repellencymentioning

confidence: 99%

Recent Progress in Preparation and Anti-Icing Applications of Superhydrophobic Coatings

et al. 2018

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Aircraft icing refers to ice formation and accumulation on the windward surface of aircrafts. It is mainly caused by the striking of unstable supercooled water droplets suspended in clouds onto a solid surface. Aircraft icing poses an increasing threat to the safety of flight due to the damage of aerodynamic shape. This review article provides a comprehensive understanding of the preparation and anti-icing applications of the superhydrophobic coatings applied on the surface of aircrafts. The first section introduces the hazards of aircraft icing and the underlying formation mechanisms of ice on the surface of aircrafts. Although some current anti-icing and de-icing strategies have been confirmed to be effective, they consume higher energy and lead to some fatigue damages to the substrate materials. Considering the icing process, the functional coatings similar to lotus leaf with extreme water repellency and unusual self-cleaning properties have been proposed and are expected to reduce the relied degree on traditional de-icing approaches and even to replace them in near future. The following sections mainly discuss the current research progress on the wetting theories of superhydrophobicity and main methods to prepare superhydrophobic coatings. Furthermore, based on the bouncing capacity of impact droplets, the dynamic water repellency of superhydrophobic coatings is discussed as the third evaluated parameter. It is crucial to anti-icing applications because it describes the ability of droplets to rapidly bounce off before freezing. Subsequently, current studies on the application of anti-icing superhydrophobic coatings including the anti-icing mechanisms and application status are introduced in detail. Finally, some limitations and issues related to the anti-icing applications are proposed to provide a future outlook on investigations of the superhydrophobic anti-icing coatings.

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Section: Dynamic Water Repellencymentioning

confidence: 99%

Recent Progress in Preparation and Anti-Icing Applications of Superhydrophobic Coatings

et al. 2018

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“…Under dynamic penetration regimes, e.g., droplet impact on a superhydrophobic surface, the transition from Cassie state may occur at a much lower pressure. [7][8][9] Balance of forces has been used to investigate the shape and stability of the air-water interface on superhydrophobic surfaces with ordered microstructures. 4,6,[10][11][12][13][14][15][16] Our group has recently used balance of forces to calculate the shape and stability of the air-water interface on superhydrophobic surfaces with randomly distributed posts of dissimilar sizes, heights, and materials 17 as well as elliptical and polygonal shallow pores.…”

Section: Introductionmentioning

confidence: 99%

Effect of fiber orientation on shape and stability of air–water interface on submerged superhydrophobic electrospun thin coatings

Emami

Tafreshi

Gad‐el‐Hak

et al. 2012

Journal of Applied Physics

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To better understand the role of fiber orientation on the stability of superhydrophobic electrospun coatings under hydrostatic pressures, an integro-differential equation is developed from the balance of forces across the air–water interface between the fibers. This equation is solved numerically for a series of superhydrophobic electrospun coatings comprised of random and orthogonal fiber orientations to obtain the exact 3D shape of the air–water interface as a function of hydrostatic pressure. More important, this information is used to predict the pressure at which the coatings start to transition from the Cassie state to the Wenzel state, i.e., the so-called critical transition pressure. Our results indicate that coatings composed of orthogonal fibers can withstand higher elevated hydrostatic pressures than those made up of randomly orientated fibers. Our results also prove that thin superhydrophobic coatings can better resist the elevated pressures. The modeling methodology presented here can be used to design nanofibrous superhydrophobic coatings for underwater applications.

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“…To estimate the surface temperature, thermocouples are frequently used, but these provide only point temperature information (Panão and Moreira 2009;Reichelt et al 2002;Serras-Pereira et al 2013). For this reason, infrared thermography-based techniques have been developed to provide spatially resolved temperature information as demonstrated by Schulz and Schmidt (2012) and Weickgenannt et al (2011). The limitation of these techniques is that they require the accurate knowledge of the surface emissivity and that makes it very difficult to measure surface temperatures through a liquid film.…”

Section: Introductionmentioning

confidence: 99%

Planar measurements of spray-induced wall cooling using phosphor thermometry

et al. 2018

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The wall cooling induced by spray impingement is investigated using phosphor thermometry. Thin coatings of zinc oxide (ZnO) phosphor were applied with a transparent chemical binder onto a steel surface. Instantaneous spatially resolved temperatures were determined using the spectral intensity ratio method directly after the injection of UV-grade hexane onto the surface using a commercial gasoline injector. The investigations showed that 2D temperature measurements with high spatial and shot-to-shot precision of, respectively, 0.5 and 0.6 K can be achieved, allowing the accurate resolution of the cooling induced by the spray. The presence of a liquid film over the phosphor coating during measurements showed no noticeable influence on the measured temperatures. However, in some cases a change in the intensity ratio at the spray impingement area, in the form of a permanent "stain", could be observed after multiple injections. The formation of this stain was less likely with increasing annealing time of the coating as well as lower plate operating temperatures during the injection experiments. Finally, the experimental results indicate a noticeable influence of the thickness of the phosphor coating on the measured spray-induced wall cooling history. Hence, for quantitative analysis, a compromise between coating thickness and measurement accuracy needs to be considered for similar applications where the heat transfer rates are very high.

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Nonisothermal drop impact and evaporation on polymer nanofiber mats

Cited by 59 publications

References 21 publications

Recent Progress in Preparation and Anti-Icing Applications of Superhydrophobic Coatings

Recent Progress in Preparation and Anti-Icing Applications of Superhydrophobic Coatings

Effect of fiber orientation on shape and stability of air–water interface on submerged superhydrophobic electrospun thin coatings

Planar measurements of spray-induced wall cooling using phosphor thermometry

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