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Atomisation process of turbulent liquid sheets : Experimental analyses and numerical developments

Abstract : Liquid fuel atomization is crucial for the performance of internal combustion engines. Through an injector, the liquid is delivered into the combustion chamber and breaks down into droplets. The finer the drops, the quicker their evaporation and the more proper their mixing with air. A proficient combustion could hence be expected, with low pollutant emissions. Atomization quality is primarily affected by the injector design and the operating conditions which shape the internal flow structure, the turbulence level, the velocity profile at the nozzle outlet, the cavitation and so forth. All these features are determinants of the breakup of the external liquid flow. Another key parameter to optimize the atomization process is the fuel physical properties. One can think of, among others, the dynamic surface tension controlled by the diffusion of the surfactants on the liquid-gas interface or the extensional viscosity which makes a liquid to become more resistant to the stretching, thereby affecting the breakup. Effects of the injector design, the operating conditions and the liquid properties on the atomization are inter-dependent. Analyses of experimental data help us to understand the involved mechanisms and their interactions. On the one hand, this is useful for the numerical developments which should be carried out depending upon the configuration. On the other hand, quantitative criterion could be established to validate the simulation results. Following the above research methodology, we aim to study the disintegration of planar turbulent liquid sheets produced by a triple-disk injector. Experimental measurements provide the sheet images, used as input for a multi-scale analysis. We investigate, thanks to the latter, the behaviours of the liquid sheet, the ligaments appearing on its edges and the resulting droplets. Moreover, two immersed boundary methods are developed, aiming to simultaneously solve the nozzle flow and the breakup process. We carry out two applications, the first one on a liquid jet ejected by a cylindrical nozzle and the other a planar sheet issuing from a triple-disk injector.
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https://tel.archives-ouvertes.fr/tel-01692017
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Submitted on : Wednesday, January 24, 2018 - 3:17:08 PM
Last modification on : Wednesday, November 3, 2021 - 4:15:57 AM
Long-term archiving on: : Thursday, May 24, 2018 - 10:06:37 PM

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  • HAL Id : tel-01692017, version 1

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Trung-Thanh Vu. Atomisation process of turbulent liquid sheets : Experimental analyses and numerical developments. Fluid mechanics [physics.class-ph]. Normandie Université, 2017. English. ⟨NNT : 2017NORMR053⟩. ⟨tel-01692017⟩

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