Behavioral patterns of drop impingement onto rigid substrates with a wide range of wettability and different surface temperatures

Li, Xiying; Ma, Xuehu; Lan, Zhong

doi:10.1002/aic.11849

Cited by 23 publications

(8 citation statements)

References 51 publications

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“…In this study, we observe and record the dynamics of droplets of various fluid properties as they impact against a rigid solid dry surface at different inclination angles, at pressures ranging from 0.2 to 6 atm. Although they are known to influence impact dynamics, the influence of surface wettability and temperature on splashing threshold was assumed to be small relative to other factors (Li et al, 2009). On the basis of the experimental results, we develop an empirical expression to predict the threshold of splashing that uses the balance between the droplet internal pressure and the droplet surface tension while considering K-H instability and gas pressure.…”

Section: Rementioning

confidence: 99%

Splashing Phenomena During Liquid Droplet Impact

Liu

Yoon

et al. 2010

Atomiz Spr

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Splashing is a phenomenon often observed during liquid droplet impact onto a solid surface. The threshold of splashing is known to be related to droplet size, impact velocity, and physical properties of the liquid, but the mechanisms that initiate splashing are not understood completely. In accordance with the Kelvin-Helmholtz (K-H) instability analysis, recent studies have shown that ambient gas density has a significant effect on the threshold and trajectory of splashing. In this study, the effects of droplet velocity, impact angle, and ambient gas pressure (or density) on the threshold of splashing and the motion of the ambient gas surrounding the droplet were examined. Experimental observations of splashing were carried out with a droplet of 1.7 mm in diameter, while varying droplet velocity, impact angle, and ambient pressure. An empirical correlation was derived using our and other published data to determine the threshold of splashing based on the aforementioned parameters. Also, a numerical simulation using the volume of fluid method was carried out to calculate the gas velocities surrounding the droplet during impact. The results of this model gave supportive evidence that K-H instability is a suitable instability theory that helps explain the splash phenomenon with consideration of the gas motion surrounding the droplet.

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Section: Rementioning

confidence: 99%

Splashing Phenomena During Liquid Droplet Impact

Liu

Yoon

et al. 2010

Atomiz Spr

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“…Significant interest in the interaction between droplets and superheated solid surfaces is evident by the plethora of publications in the last few years [1,2,3,4,5,6,7,8,9,10]. Droplet impingement is present in a wide array of applications including spray cooling, coating, biochemical reactions and combustion, and is the focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

“…The maximum spread diameter, D max , at the LFP provides insight to the dynamics of the system as well and has been explored in multiple previous works [9,20,21,22,23]. Tran et al showed that D max is larger at the LFP on a hydrophilic surface than on a superhydrophobic surface maintained at room temperature for We < 1000, although both exhibit similar spreading/retracting dynamics [12].…”

Section: Introductionmentioning

confidence: 99%

“…Though previous research has covered a broad range of experimental conditions and provided great insight into the physics of the interaction between a droplet and a heated hydrophilic surface, impingement on hydrophobic and superhydrophobic surfaces at elevated temperatures has received only modest attention [9,25,26,18]. Park et al performed experiments of droplets (360 µm in diameter) impinging at W e = 60 on hydrophilic and hydrophobic surfaces over a temperature range of 110 • C to 210 • C [26].…”

Section: Introductionmentioning

confidence: 99%

“…They reported that the residence time was generally lower for impingement on a hydrophobic substrate, but no information regarding Leidenfrost transition temperatures or maximum spread diameter at the LFP was given. In a different work, Li et al reported hydrodynamic behavior of impinging droplets at W e = 22, such as droplet height, diameter and dynamic contact angles, on surfaces of varying wettability (hydrophilic to superhydrophobic) but the maximum surface temperature explored was limited to 110 • C [9]. More recently, Zhang et al explored impingement on superhydrophobic surfaces with microscale posts in a square lattice [18] for Weber numbers up to 85 and temperatures up to 320 • C. They mapped different behaviors including contact boiling and rebound with and without satellite droplets (at around the LFP).…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamics of droplet impingement on hot surfaces of varying wettability

Clavijo

Crockett

Maynes

2017

International Journal of Heat and Mass Transfer

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This work presents on the hydrodynamics of water droplet impingement on superheated solid surfaces across the entire wettability spectrum: superhydrophilic, hydrophilic, hydrophobic and superhydrophobic. While a large body of work exists on droplet impingement on hydrophilic and superhydrophilic surfaces, impingement on the latter two has been largely neglected and the present results show that dynamics are dramatically different. Experiments ranging in surface temperature from 125 • C to 415 • C and Weber numbers from 10 to 225 were performed and analyzed using high-speed imaging. Some of the most striking differences are as follows. While atomization is always present for impingement on the hydrophilic and superhydrophilic surfaces at temperatures below the Leidenfrost point, atomization is absent at low Weber numbers and at low excess surface temperatures on the hydrophobic surface. At high surface temperatures, the attraction of vapor bubbles on the hydrophobic surface allows a vapor blanket to form more readily thus leading to Leidenfrost behavior at a much lower temperature than classically observed on a hydrophilic surface. One of the most interesting phenomenon that will be discussed includes what will be described as a "pseudo-Leidenfrost" state for impingement on the superhydrophobic surface. Because water can be suspended at the peaks of the roughness on a superhydrophobic interface, vapor escapes from underneath the droplet thus mimicking Leidenfrost behavior for all excess temperatures. This results in minimal atomization for superhydrophobic impingement over the entire regime explored. Finally, maximum spread diameters for Leidenfrost impingement are tabulated as a function of the Weber number for all surfaces and are shown to be larger on the smooth surfaces than on the textured ones indicating that droplet spreading at the Leidenfrost point is not independent

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Spray impact resistance of a superhydrophobic nanocomposite coating

et al. 2014

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The performance of a polyurethane/organoclay superhydrophobic nanocomposite modified with perfluoroalkyl methacrylic copolymer in the presence of a high‐pressure air‐water spray which mimics an icing cloud impact is investigated in this study. To quantify the average velocites of droplets impacting the superhydrophobic samples, a computational study was performed. Such a study is important to understand the interaction between the jet and surface. Impacting velocities for three different testing conditions were estimated to be 14.5, 4.5, and 3.4 m/s. Liquid saturation did not occur immediately, but over time, the high mass flow rate of water led to antiwetting performance degradation. Upon evaporation, contact angle returned to pretest values, indicating little mechanical erosion. This was consistent with scanning electron microscopy which showed that the nano and microstructure was preserved, and with energy‐dispersive X‐ray spectroscopy, which showed no surface chemistry change after testing. However, sliding angle showed stronger degradation, especially at higher impact velocities. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3025–3032, 2014

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Behavioral patterns of drop impingement onto rigid substrates with a wide range of wettability and different surface temperatures

Cited by 23 publications

References 51 publications

Splashing Phenomena During Liquid Droplet Impact

Splashing Phenomena During Liquid Droplet Impact

Hydrodynamics of droplet impingement on hot surfaces of varying wettability

Spray impact resistance of a superhydrophobic nanocomposite coating

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