Bubble formation in a coflow configuration in normal and reduced gravity

Bhunia, Avijit; Pais, Salvatore Cezar; Kamotani, Y.; Kim, Iee-Hwan

doi:10.1002/aic.690440704

Cited by 64 publications

(39 citation statements)

References 17 publications

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“…In the case of bubble generation, buoyancy alone is usually enough on Earth to produce detachment of bubbles from the injector (Kulkarni and Joshi 2005). However in microgravity environments this is not the case, and different methods have been devised to produce bubble detachment, such as the employ of cross-flow and co-flow configurations (Pampering and Rath 1995;Bhunia et al 1998;Forrester and Rielly 1998), the application of fields (Di Marco et al 2003;Iacona et al 2006), etc. Performance of these methods was not completely satisfactory for certain purposes, in the sense that bubble sizes were typically too large, with large size dispersion, and the methods were sensitive to the gravity level.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of a Microchannel Bubble Injector for Microgravity Applications

Calderón

Ruíz

Casademunt

et al. 2008

Microgravity Sci. Technol

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We perform a quantitative characterization of a microbubble injector in conditions relevant to microgravity. The injector pregenerates a slug flow by using a capillary T-junction, whose operation is robust to changes in gravity level. We address questions regarding the performance under different injection conditions. In particular we focus on the variation of both gas and liquid flow rates. The injection performance is characterized by measuring bubble injection frequency and bubble sizes. We obtain two distinct working regimes of the injector and identify the optimal performance as the crossover region between them.

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Section: Introductionmentioning

confidence: 99%

Experimental Study of a Microchannel Bubble Injector for Microgravity Applications

Calderón

Ruíz

Casademunt

et al. 2008

Microgravity Sci. Technol

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“…The absence of the buoyancy force in the microgravity environment makes necessary specific methods to detach bubbles from the generator device. Typically the liquid flow is used to aid bubble detachment, both in co-flow configuration [4], in which liquid flows parallel to the gas injection direction, and cross-flow configuration [5], in which liquid flows perpendicularly to the gas injection. We proposed a configuration [6] which is a particular case of the cross-flow one.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the performance of a minibubble generator in conditions relevant to microgravity

Calderón

González-Cinca

Ruíz

et al. 2010

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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We perform a characterization of a recently reported minibubbles (bubbles with a diameter of the order of 10 -3 m) generator in microgravity related conditions. Generation of bubbles is based on the generation of a slug flow in a capillary T-junction, whose operation is robust to changes in the gravity level. We address questions regarding the performance under different working regimes. In particular, we focus on the regimes found within a large range of gas and liquid injection flow rates. The injection performance is characterized by measuring bubble generation frequency. We propose curves obtained empirically for the behavior of generation frequency and crossover between regimes.

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“…In additional experiments with larger gas fluxes [8], they studied the effects of different liquid flow conditions in the growth and detachment of bubbles. Bhunia et al [9] concluded that gas momentum enhanced bubble detachment, whereas surface tension inhibited bubble detachment. In contrast, the liquid drag and the inertial forces acted as enhancing or inhibiting factors for bubble detachment, depending on the relative velocities of the bubbles and the flowing liquid.…”

mentioning

confidence: 99%

Generation of a Monodisperse Microbubble Jet in Microgravity

et al. 2008

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A new method to create a jet of a virtually monodisperse microbubble suspension of prescribed bubble size into a quiescent cavity is proposed. The method is insensitive to gravity and is based on the creation of a slug flow at a T junction in a capillary tube before injection. We develop a theoretical analysis that establishes the validity and efficiency of the method, as controlled by the crossflow Weber number, and yields a simple explicit prediction for the bubble size in terms of the injection parameters. The method operates efficiently for small Weber numbers, yet it generates small bubbles of very uniform size. The reduced size dispersion is also explained within the theoretical model. The method of bubble formation, injection, and spreading by the resulting turbulent jet is validated experimentally in 4.7 s of free fall in the drop tower at the University of Bremen. Experiments demonstrate the physical principle behind the method of bubble formation and allow us to explore the dynamics of the resulting bubble jet after injection of the slug flow into a quiescent cavity in microgravity conditions as an efficient method of bubble spreading and transport. Detailed measurements of average local velocities show that bubbles are essentially passive with respect to the carrier mean flow, and the inherent turbulence of the flow is crucial for optimal spreading of the bubble distribution and reduction of bubble coalescence. The shape of the bubble jet is studied as a function of the Reynolds number. Finally, the degree of coalescence is also characterized and found to be remarkably small.

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Bubble formation in a coflow configuration in normal and reduced gravity

Cited by 64 publications

References 17 publications

Experimental Study of a Microchannel Bubble Injector for Microgravity Applications

Experimental Study of a Microchannel Bubble Injector for Microgravity Applications

Characterization of the performance of a minibubble generator in conditions relevant to microgravity

Generation of a Monodisperse Microbubble Jet in Microgravity

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