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Published January 2005 | public
Journal Article

Modeling of multicomponent-fuel drop-laden mixing layers having a multitude of species

Abstract

A formulation representing multicomponent-fuel (MC-fuel) composition as a probability distribution function (PDF) depending on the molar mass is used to construct a model of a large number of MC-fuel drops evaporating in a gas flow, so as to assess the extent of fuel specificity on the vapor composition. The PDF is a combination of two Gamma PDFs, which was previously shown to duplicate the behavior of a fuel composed of many species during single drop evaporation. The conservation equations are Eulerian for the flow and Lagrangian for the physical drops, all of which are individually followed. The gas conservation equations for mass, momentum, species, and energy are complemented by differential conservation equations for the first four moments of the gas-composition PDF; all coupled to the perfect gas equation of state. Source terms in all conservation equations couple the gas phase to the drops. The drop conservation equations for mass, position, momentum, and energy are complemented by differential equations for four moments of the liquid-composition PDF. The simulations are performed for a three-dimensional mixing layer whose lower stream is initially laden with drops. Initial perturbations excite the layer to promote the double pairing of its four initial spanwise vortices to an ultimate vortex. The drop temperature is initially lower than that of the surrounding gas, initiating drop heating and evaporation. The results focus on both evolution and the state of the drops and gas when layers reach a momentum-thickness maximum past the double vortex pairing; particular emphasis is on the gas composition. Comparisons between simulations with n-decane, diesel, and three kerosenes show that at same initial Reynolds number and Stokes number distribution, a single-component fuel cannot represent MC fuels. Substantial differences among the MC-fuel vapor composition indicate that fuel specificity must be captured for the prediction of combustion.

Additional Information

© 2004 The Combustion Institute. Published by Elsevier Inc. Available online 3 September 2004. 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 and Mr. D. Hooker 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. We thank Dr. K.G. Harstad for helpful discussions. Computational resources were provided by the supercomputing facility at JPL.

Additional details

Created:
August 19, 2023
Modified:
October 17, 2023