Journal ArticleDOI
On the collision of a droplet with a solid surface
Sanjeev Chandra,C.T. Avedisian +1 more
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In this paper, the collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method, which provided clear images of the droplet structure during the deformation process.Abstract:
The collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method. The intent was to provide clear images of the droplet structure during the deformation process. The ambient pressure (0.101 MPa), surface material (polished stainless steel), initial droplet diameter (about 1.5 mm), liquid (n-heptane) and impact Weber number (43) were fixed. The primary parameter was the surface temperature, which ranged from 24 degrees C to above the Leidenfrost temperature of the liquid. Experiments were also performed on a droplet impacting a surface on which there existed a liquid film created by deposition of a prior droplet. The evolution of wetted area and spreading rate, both of a droplet on a stainless steel surface and of a droplet spreading over a thin liquid film, were found to be independent of surface temperature during the early period of impact. This result was attributed to negligible surface tension and viscous effects, and in consequence the measurements made during the early period of the impact process were in good agreement with previously published analyses which neglected these effects. A single bubble was observed to form within the droplet during impact at low temperatures. As surface temperature was increased the population of bubbles within the droplet also increased because of progressive activation of nucleation sites on the stainless steel surface. At surface temperatures near to the boiling point of heptane, a spoke-like cellular structure in the liquid was created during the spreading process by coalescence of a ring of bubbles that had formed within the droplet. At higher temperatures, but below the Leidenfrost point, numerous bubbles appeared within the droplet, yet the overall droplet shape, particularly in the early stages of impact (< 0.8 ms), was unaffected by the presence of these bubbles. The maximum value of the diameter of liquid which spreads on the surface is shown to agree with predictions from a simplified model.read more
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Study of the surface wettability effect on dynamic characteristics of droplet impacting a tube with different curvature ratios
TL;DR: In this paper, surface wettability plays a significant role on the dynamic characteristics of droplet impact, and the effect of surface Wettability is analyzed with the curvature ratios of 1.4, 0.43, and 0.26, respectively.
Journal ArticleDOI
Experimental Study of Diesel-Fuel Droplet Impact on a Similarly Sized Polished Spherical Heated Solid Particle
TL;DR: The effects of the Weber number and surface temperature on the wettability dynamics were examined and the temporal variations of the dynamic contact angle, dimensionless spreading diameter, and liquid film thickness forming on the solid particle were measured.
Journal ArticleDOI
The interaction of falling and sessile drops on a hydrophobic surface
TL;DR: In this paper, the influence of the Weber number, We, on drop spreading is explored. But the authors focus on the behavior of falling water drops impacting a sessile drop at rest.
Journal ArticleDOI
Influences of substrate wettability and liquid viscosity on isothermal spreading of liquid droplets on solid surfaces
Chun Yang,K. C. Leong +1 more
TL;DR: In this article, the final spread of a liquid droplet on a flat solid surface was experimentally studied at room temperature, and it was found that the spreading meniscus of water droplets in the final equilibrium state corresponds to the static contact angles of the substrates.
Journal ArticleDOI
Droplet Behavior on a Rotating Surface for Atomization-Based Cutting Fluid Application in Micromachining
TL;DR: In this paper, the droplet behavior on a rotating surface has been studied to better understand the physics underlying atomized cutting fluid application, and the cutting performance evaluated for varying cutting fluids and at different droplet speeds.
References
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Surface Tension as the Cause of Bénard Cells and Surface Deformation in a Liquid Film
TL;DR: Benard as mentioned in this paper observed a cellular deformation produced on the free surface of a liquid film the bottom surface of which (in contact with a floor) was uniformly heated and hotter than its top surface.
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The Homogeneous Nucleation Limits of Liquids
TL;DR: In this article, a critical compilation of the homogeneous nucleation limits of liquids is provided, where data for 90 pure substances and 28 mixtures have been compiled over a range of pressures, nucleation rates, and compositions.
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