A study of droplet impact on static films using the BB-LIF technique

Hann, David; Cherdantsev, Andrey V.; Mitchell, Antony J.; McCarthy, Ian N.; Hewakandamby, Buddhika N.; Simmons, Kathy

doi:10.1007/s00348-016-2132-x

Cited by 22 publications

(9 citation statements)

References 21 publications

(28 reference statements)

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“…4b are obtained from Eqs. (5), (6), and (7), respectively, with h jet obtained through image processing. The total energy obtained from the experiment in the late stage of the jet, i.e.…”

Section: Elongation Of the Central Jetmentioning

confidence: 99%

Impact of droplets on immiscible liquid films

Che

Matar

2018

Soft Matter

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The impact of droplets on liquid films is a ubiquitous phenomenon not only in nature but also in many industrial applications. Compared to the widely-studied impact of droplets on films of identical fluids, the impact of droplets on immiscible films has received far less attention. In the present work, we show using high-speed imaging that immiscibility has a profound effect on the impact dynamics. The impact of a water droplet on an oil film leads to the formation of a compound crown followed by a central jet, whereas that of an oil droplet on a water film results in rapid spreading on the film surface driven by a large, positive spreading factor. In the former scenario, the central jet occurs due to the severe stretching of the droplet during the formation of the crown and then the retraction of the droplet by capillarity, which leads to the collision of fluid at the impact point. A model for the elongation dynamics of the central jet is proposed based on energy conservation. The effects of key parameters controlling the impact process are analysed, including the droplet Ohnesorge and Weber numbers, the viscosity ratio, and the dimensionless film thickness. Different impact outcomes are discussed, such as bouncing, deposition, and oscillation of the impact droplet, the formation and collapse of the compound crown, and the formation and tip-pinching of the central jet. This study not only provides physical insights into the impact dynamics, but could also facilitate the control and optimisation of the droplet impact process in a number of applications as highlighted herein.

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“…4b are obtained from Eqs. (5), (6), and (7), respectively, with h jet obtained through image processing. The total energy obtained from the experiment in the late stage of the jet, i.e.…”

Section: Elongation Of the Central Jetmentioning

confidence: 99%

Impact of droplets on immiscible liquid films

Che

Matar

2018

Soft Matter

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“…The videos from the high-speed camera were analysed using MATLAB software similar to that of the work from [5]. Any measurements from the images were originally taken in pixels and then calibrated to mm.…”

Section: Experimental Methodologymentioning

confidence: 99%

“…This study is therefore relevant to industry by developing an understanding to how temperature may affect the outcome of droplet impact onto liquid films. There are several reviews of the droplet impact outcomes, such as [3] , and there are a number of theories about the crater evolution [4] for droplets of same temperature and liquid impacting on a film [5]. However there are few studies on droplets of different temperature to the film [6,7].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Film Temperature on crater morphology during the impact of a single droplet

2016

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Abstract. The effect of varying the film temperature from 15C to 60 C is investigated using high speed video imaging. It is demonstrated that increasing the temperature difference between the droplet and film liquid changes the size and frequency of the secondary droplets. The impact can be split into three regimes. In the crater expansion regime, the crater follows a self-similar behaviour. In the second stage, the crater becomes deeper and wider at higher temperatures possibly due to decrease in the viscosity or surface tension. It is seen that the crater collapse is less dependent on the temperature and occurs at fixed time for a particular Webber number.

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“…This can occur as a result of detachment from larger droplets (2 in Figure 3), detachment from the liquid film on the vane due to collision with large drops or due to droplets dropping from the film due to interfacial shear stress (3 and 4 in Figure 3) [5]. The destruction of droplets caused by the interaction with the continuous phase can be estimated based on the Weber number [6]:…”

Section: Secondary Droplets Generationmentioning

confidence: 99%

Numerical investigation of a moisture wave-type vane separator

2019

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This study aims to determine the appropriate method for modeling separation processes in wave-type moisture vane separators and to analyze possible design improvements of the typical wave-type vane separator using numerical simulation methods. It discusses conditions of the secondary droplets generation phenomena. The applicability of the particle transport method for modeling the working process in wave-type vane separators is confirmed. The study explores the water droplets distribution pattern in the dispersed two-phase flow of a separator. A numerical study of the workflow in the typical steam-water separator with wave-type vanes was carried out. A dispersed two-phase flow in a separator is modelled as two separate flows. Dry saturated steam is considered as a continuous medium using the Euler method; the liquid phase is represented as a stream of water droplets described by the Lagrange method. Authors propose an option of modernization of the separator design applying three drainage channels on the path of small droplets.

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A study of droplet impact on static films using the BB-LIF technique

Cited by 22 publications

References 21 publications

Impact of droplets on immiscible liquid films

Impact of droplets on immiscible liquid films

The Effect of Film Temperature on crater morphology during the impact of a single droplet

Numerical investigation of a moisture wave-type vane separator

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