Deformation Behaviors of a Liquid Droplet Impinging onto Hot Metal Surface

Akao, Fujio; Araki, Koji; Mori, Sigekatsu; Moriyama, Akira

doi:10.2355/isijinternational1966.20.737

Cited by 101 publications

(39 citation statements)

References 2 publications

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“…The critical boundary at which the disintegration of droplets occurs has been discussed in relation to the Weber number [7]. Further, the maximum diameter of spreading droplets, the time required for the circular water film to reach the maximum spreading diameter, and the droplet resident time on a hot surface have been correlated via functions of the Weber number [8][9][10][11][12]. The predictions are in moderate agreement with experiments.…”

Section: Introductionmentioning

confidence: 85%

“…Further, d max presents the maximum spreading length in the x direction. A similar modification was employed to correlations proposed by Akao et al [9], Ueda et al [8] and Araki and Moriyama [37]. It is clear that…”

Section: B Collision Behavior Of Droplets On the Solid At 500 °Cmentioning

confidence: 93%

“…They proposed experimental correlations capable of predicting the maximum spreading length of a droplet in the x direction based on the Weber number, We n , alone, as shown in Table 2. Incidentally, in cases of normal collisions, other researchers [8][9][10]37] have proposed experimental formulae capable of predicting three parameters: (a) the maximum spreading diameters of a droplet, (b) the time required for the circular water film to reach the maximum spreading diameter, and (c) the resident time of droplets on a hot surface from the moment of impact to rebounding off the surface, as shown in Table 2. They are correlated with functions of the Weber numbers defined in Eq.…”

Section: B Collision Behavior Of Droplets On the Solid At 500 °Cmentioning

confidence: 99%

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An Experimental Study on the Oblique Collisions of Water Droplets With a Smooth Hot Solid

Fujimoto

Doi

Takuda

2012

Journal of Fluids Engineering

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The motions of liquid droplets impinging on a solid substrate have been studied experimentally in fundamental research on various types of industrial applications, including spray cooling. The oblique collision of a single water droplet with a hot Inconel 625 alloy surface has been investigated by means of a two-directional flash photography technique that uses two digital still cameras and three flash units. The experiments were conducted under the following conditions. The preimpact diameter of the droplets was approximately 0.6 mm, the impact velocity was 1.9–3.1 m/s, and the temperature of the Inconel 625 alloy surface ranged from 170 °C to 500 °C. The impact angle of droplets on the solid surface was in the range 45 deg–90 deg. Experiments using 2.5 mm diameter droplets at an impact velocity of 0.84–1.4 m/s were also conducted at the surface temperature of 500 °C. At surface temperatures of 200 °C, 300 °C, and 400 °C, the droplet deforms into an asymmetric shape and moves downward along the tilted surface. Numerous secondary droplets jet upward from the deforming droplet as a result of the blowout of vapor bubbles into the atmosphere. At a surface temperature of 500 °C and a low Weber number Wen based on the normal velocity component to the solid surface, no secondary droplets are observed. The droplet rebounds off the solid without disintegrating. The droplet becomes almost axisymmetric in shape during the collision regardless of the impact angle. The dimensionless collision behaviors of large and small droplets were similar for the same Wen when the temperature was 500 °C. Using Wen, we investigated the deformation characteristics of droplets in oblique collisions.

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Section: Introductionmentioning

confidence: 85%

Section: B Collision Behavior Of Droplets On the Solid At 500 °Cmentioning

confidence: 93%

Section: B Collision Behavior Of Droplets On the Solid At 500 °Cmentioning

confidence: 99%

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An Experimental Study on the Oblique Collisions of Water Droplets With a Smooth Hot Solid

Fujimoto

Doi

Takuda

2012

Journal of Fluids Engineering

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“…Empirical correlations: Scaling analysis has been applied to study the D max based on experimental data of droplet impact on impermeable surfaces. One of the frequently used empirical correlations in commercial CFD codes FLUENT, STAR-CCM+, VECTIS was reported by Akao et al (Akao et al, 1980):…”

Section: Maximum Spreading Diameter ( )mentioning

confidence: 99%

The dynamics of droplet impact on a heated porous surface

Zhao

Hargrave

Versteeg

et al. 2018

Chemical Engineering Science

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In this paper, droplet impact on a porous surface is experimentally investigated over a wide range of Weber numbers and surface temperatures. Regime transition criteria have been deduced to determine droplet post-impingement behaviour as a function of the Weber number and surface temperature for which a droplet impacting on a porous surface. Based on the energy balance, an analytical model with improved boundary layer description is proposed to predict maximum spreading of droplet following impact on porous surfaces when the effect of heat transfer is negligible. The results of the model indicate that the spreading process after droplet impact on porous surfaces is governed by the viscous dissipation and matric potential. The maximum-spread model predictions agreed well with experimental measurements reported in this paper and the literature over a large range of Weber numbers and different porous surfaces. Highlights: •The dynamics of droplet impact on a heated porous surface is studied experimentally. •A new impact regime map together with regime transition criteria is proposed to determine droplet post-impingement behaviour. •Significant differences are found between droplet impact on impermeable surfaces and porous surfaces. •An analytical model with improved boundary layer description is developed to predict maximum spreading. •The maximum-spread model predictions agree well with experiments.

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“…In reality, from an experimental point of view, the collision dynamics of a liquid droplet impinging on a hot surface have been investigated by many researchers. Wachters and Westerling [3], Ueda et al [4], Akao et al [7] and Shoji et al [8] studied the deformation process of some types of liquid drops on a hot metallic surface. Chandra and Avedisian [9] investigated the effect of surface temperature on the deformation process of an n-heptane droplet.…”

mentioning

confidence: 99%

Deformation process of a droplet impinging on a hot oxide‐scaled surface above the Leidenfrost temperature

1997

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This paper is concerned with the collision dynamics of a water droplet impinging on a hot surface heated to above the Leidenfrost temperature, focusing upon the case where the impingement side is rough (oxide‐scaled) with an oxide film. The rough surface has been artificially made by rapidly quenching as‐rolled stainless steel by water spraying, after it has been heated to 1000°C in a furnace. A sequence of photographs showing the progressive stages of droplet deformation have been taken on several Weber number conditions. It has been found that the droplet configuration is not axially symmetric around the initial impact point even at an early stage immediately after collision and that the irregularity of the droplet configuration is amplified as the droplet deformation proceeds. With increasing Weber number, the irregularity has been seen to be more remarkable in the later stage and finally the droplet breaks up into some parts. Therefore, the critical Weber number to specify whether or not the droplet is disintegrated on the rough surface has been found to become small compared with the smooth surface case.

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Deformation Behaviors of a Liquid Droplet Impinging onto Hot Metal Surface

Cited by 101 publications

References 2 publications

An Experimental Study on the Oblique Collisions of Water Droplets With a Smooth Hot Solid

An Experimental Study on the Oblique Collisions of Water Droplets With a Smooth Hot Solid

The dynamics of droplet impact on a heated porous surface

Deformation process of a droplet impinging on a hot oxide‐scaled surface above the Leidenfrost temperature

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