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Bubble formation at a flexible orifice with liquid cross-flow

Loubiere, Karine and Castaignède, Vincent and Hebrard, Gilles and Roustan, Michel Bubble formation at a flexible orifice with liquid cross-flow. (2004) Chemical Engineering and Processing, vol. 43 (n° 6). pp. 717-725. ISSN 0255-2701

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Official URL: http://dx.doi.org/10.1016/S0255-2701(03)00017-5

Abstract

In waste water treatment, biological processes for denitrification and nitrification are performed using oxidation ditches. In these reactors, the mixing and the aeration functions are dissociated: a bubble cloud is generated from flexible membrane spargers and is subjected to a horizontal liquid flow. The objective of this paper is to study the effects of the liquid crossflow on the bubble formation at a single flexible orifice in water. The several forces acting on the forming bubble have been modelled in order to understand the dynamics of the bubble growth and detachment. The bubble detachment is controlled by the drag force due to the liquid motion and not by the buoyancy force. The experimental analysis of the bubble growth has shown that, under liquid cross-flow conditions, the bubbles move downstream and are flattened during their growth (position of the bubble centre of gravity, bubble inclination angle). The bubbles spread over the orifice surface, and the advancing and the receding bubble angles were measured. The detached bubbles have significantly smaller sizes and higher frequencies when compared to bubble formation under quiescent liquid conditions.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Chemical Engineering and Processing website : http://www.sciencedirect.com/science/journal/02552701
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National des Sciences Appliquées de Toulouse - INSA
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Deposited By:Karine LOUBIERE

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