Behavior of chemicals in the seawater column by shadowscopy

• Autores: Mélanie Fuhrer, Laurent Aprin, Stéphane Le Floch, Gilles Dusserre, Pierre Slangen
• Localización: SPECKLE 2012: V International Conference on Speckle Metrology : 10-12 september 2012 : Vigo, Spain / Ángel Manuel Fernández Doval (ed. lit.), María Cristina Trillo Yáñez (ed. lit.), José Carlos López Vázquez (ed. lit.), 2012, ISBN 9780819490902
• Idioma: inglés
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• Resumen

  • Ninety percent of the Global Movement of Goods transit by ship. The transportation of HNS (Hazardous and Noxious Substances) in bulk highly increases with the tanker traffic. The huge volume capacities induce a major risk of accident involving chemicals. Among the latest accidents, many have led to vessels sinking (Ievoli Sun, 2000 - ECE, 2006). In case of floating substances, liquid release in depth entails an ascending two phase flow. The visualization of that flow is complex. Indeed, liquid chemicals have mostly a refractive index close to water, causing difficulties for the assessment of the two phase medium behavior. Several physics aspects are points of interest: droplets characterization (shape evolution and velocity), dissolution kinetics and hydrodynamic vortices. Previous works, presented in the 2010 Speckle conference in Brazil, employed Dynamic Speckle Interferometry to study Methyl Ethyl Ketone (MEK) dissolution in a 15 cm high and 1 cm thick water column. This paper deals with experiments achieved with the Cedre Experimental Column (CEC - 5 m high and 0.8 m in diameter). As the water thickness has been increased, Dynamic Speckle Interferometry results are improved by shadowscopic measurements. A laser diode is used to generate parallel light while high speed imaging records the products rising. Two measurements systems are placed at the bottom and the top of the CEC. The chemical class of pollutant like floaters, dissolvers (plume, trails or droplets) has been then identified. Physics of the two phase flow is presented and shows up the dependence on chemicals properties such as interfacial tension, viscosity and density. Furthermore, parallel light propagation through this disturbed medium has revealed trailing edges vortices for some substances (e.g. butanol) presenting low refractive index changes