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Direct numerical simulation of gaseous mixing layers laden with multicomponent-liquid drops: liquid-specific effects

Le Clercq, Patrick C. and Bellan, Josette (2005) Direct numerical simulation of gaseous mixing layers laden with multicomponent-liquid drops: liquid-specific effects. Journal of Fluid Mechanics, 533 . pp. 57-94. ISSN 0022-1120.

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A representation of multicomponent-liquid (MC-liquid) composition as a linear combination of two single-Gamma probability distribution functions (PDFs) is used to describe a large number of MC-liquid drops evaporating in a gas flow. The PDF, called the double-Gamma PDF, depends on the molar mass. The gas-phase conservation equations are written in an Eulerian frame and the drops are described in a Lagrangian frame. Gas conservation equations for mass, momentum, species and energy are combined with differential conservation equations for the first four moments of the gas-composition PDF and coupled to the perfect gas equation of state. Source terms in all conservation equations account for the gas/drop interaction. The drop governing equations encompass differential conservation statements for position, mass, momentum, energy and four moments of the liquid-composition PDF. Simulations are performed for a three-dimensional mixing layer whose lower stream is initially laden with drops colder than the surrounding gas. Initial perturbations excite the layer to promote the double pairing of its four initial spanwise vortices to an ultimate vortex. During the layer evolution, the drops heat and evaporate. The results address the layer evolution, and the state of the gas and drops when layers reach a momentum-thickness maximum past the double vortex pairing. Of interest is the influence of the liquid composition on the development of the vortical features of the flow, on the vortical state reached after the second pairing, and on the gas temperature and composition. The MC-liquid simulations are initiated with a single-Gamma PDF composition so as to explore the development of the double-Gamma PDF. Examination of equivalent simulations with n-decane, diesel and three kerosenes as the liquid, permits assessment of the single-species versus the MC-liquid aspect, and of mixture composition specific effects. Global layer growth and global rotational characteristics are unaffected by liquid specificity; however, the global mixing is highly liquid-specific. Also liquid-specific is the evolution of the ensemble-averaged drop characteristics and of the volumetric averages representing the gas composition. Visualized rotational characteristics show that the small-scale vortical activity increases with increased fuel volatility, which is confirmed by analysis of the vorticity budgets. Homogeneous-plane-average budgets of the vorticity and vorticity-magnitude equations indicate that the stretching and tilting, and momentum-source terms are responsible for the difference among simulations. For all MC liquids, the gas displays a high level of composition heterogeneity, which can directly be traced to the original PDF representing the MC-liquid composition. Under most conditions, the single-Gamma PDF develops into a double-Gamma PDF; however, the extent of this transformation, indicative of vapour condensation onto drops, is not readily parametrized by the liquid volatility, initial carrier-gas temperature or trace vapour in the initial gas.

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Bellan, Josette0000-0001-9218-7017
Additional Information:© 2005 Cambridge University Press. Received 19 July 2004 and in revised form 20 December 2004. Published online: 15 June 2005. This study was conducted at the Jet Propulsion Laboratory (JPL), California Institute of Technology (Caltech), under the partial sponsorship of the Donors of The Petroleum Research Fund administered by the American Chemical Society through a grant (to J.B.) for Caltech Post Doctoral Fellow support, the US Department of Energy with Ms R. Danz, Mr D. Hooker, Mr S. Waslo and Ms D. Haught as contract monitors, under an agreement with the National Aeronautics and Space Administration, and the Air Force Research Laboratory, Wright Patterson Air Force Base with Dr J.T. Edwards as Technical Monitor. Additional sponsorship was provided by the Office National d’Études et de Recherches Aérospatiales for Post Doctoral support. Computational resources were provided by the supercomputing facility at JPL.
Funding AgencyGrant Number
American Chemical Society Petroleum Research FundUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Office National d’Études et de Recherches AérospatialesUNSPECIFIED
Record Number:CaltechAUTHORS:20171024-094958414
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Official Citation:LE CLERCQ, P., & BELLAN, J. (2005). Direct numerical simulation of gaseous mixing layers laden with multicomponent-liquid drops: Liquid-specific effects. Journal of Fluid Mechanics, 533, 57-94. doi:10.1017/S0022112005003940
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82613
Deposited By: Tony Diaz
Deposited On:24 Oct 2017 20:15
Last Modified:09 Mar 2020 13:18

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