Modeling of Multicomponent Fuels Using Continuous Distributions with Application to Droplet Evaporation and Sprays

Lippert, Andreas; Reitz, Rolf D.

doi:10.4271/972882

Cited by 106 publications

(38 citation statements)

References 23 publications

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“…Based on the CT approach, Tamim and Hallett 23 and Hallett 26 have developed a model for the evaporation of a single, isolated drop of fuel that is a mixture of very many species. Furthermore, the same model has been used by Lippert and Reitz 27 as a building block in codes devoted to practical applications. The present study adopts the CT approach and utilizes it in a fundamental study of the coupled interaction between a multitude of drops and the flow in a temporal mixing layer at atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Clercq

Bellan

2004

Physics of Fluids

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A model of a temporal three-dimensional mixing layer laden with fuel drops of a liquid containing a large number of species is derived. The fuel model is based on continuous thermodynamics, whereby the composition is statistically described through a distribution function parametrized on the species molar weight. The drop temperature is initially lower than that of the carrier gas, leading to drop heat up and evaporation. The model describing the changes in the multicomponent ͑MC͒ fuel drop composition and in the gas phase composition due to evaporation encompasses only two more conservation equations when compared with the equivalent single-component ͑SC͒ fuel formulation. Single drop results of a MC fuel having a sharply peaked distribution are shown to compare favorably with a validated SC-fuel drop simulation. Then, single drop comparisons are performed between results from MC fuel and a representative SC fuel used as a surrogate of the MC fuel. Further, two mixing layer simulations are conducted with a MC fuel and they are compared to representative SC-fuel simulations conducted elsewhere. Examination of the results shows that although the global layer characteristics are generally similar in the SC and MC situations, the MC layers display a higher momentum-thickness-based Reynolds number at transition. Vorticity analysis shows that the SC layers exhibit larger vortical activity than their MC counterpart. An examination of the drop organization at transition shows more structure and an increased drop-number density for MC simulations in regions of moderate and high strain. These results are primarily attributed to the slower evaporation of MC-fuel drops than of their SC counterpart. This slower evaporation is due to the lower volatility of the higher molar weight species, and also to condensation of already-evaporated species on drops that are transported in regions of different gas composition. The more volatile species released in the gas phase earlier during the drop lifetime reside in the lower stream while intermediary molar weight species, which egress after the drops are entrained in the mixing layer, reside in the mixing layer and form there a very heterogeneous mixture; the heavier species that evaporate later during the drop lifetime tend to reside in regions of high drop number density. This leads to a segregation of species in the gas phase based on the relative evaporation time from the drops. The ensemble-average drop temperature becomes eventually larger/smaller than the initial drop temperature in MC/SC simulations. Neither this species segregation nor the drop temperature variation with respect to the initial temperature or as a function of the mass loading can be captured by the SC-fuel simulations.

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Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Clercq

Bellan

2004

Physics of Fluids

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“…Recent models of MC hydrocarbon-mixture drops based on a statistical rather than deterministic species representation have raised the possibility of simulating the full complexity of MC-liquid sprays Hallett 2000;Lippert & Reitz 1997;Harstad, Le Clercq & Bellan 2003;Arias-Zugasti & Rosner 2003;Harstad & Bellan 2004) and thus to enable differentiating among a myriad of species. The common feature of all these recent models is the utilization of continuous thermodynamics (CT), a theory developed by Gal-Or, Cullinan & Galli (1975) and by Cotterman, Bender & Prausnitz (1985).…”

Section: Introductionmentioning

confidence: 99%

“…It is this segregation, which is important in many processes (including combustion, spray dispensing and atmospheric dispersion), that cannot be captured by an SCliquid approximation. Harstad et al (2003) have shown that SGPDF models applied to drop evaporation Hallett 2000;Lippert & Reitz 1997) are, however, restricted to applications where the gas surrounding the drop contains only small quantities of vapour species mixed with a carrier gas (e.g. air).…”

Section: Introductionmentioning

confidence: 99%

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

Clercq

Bellan

2005

J. Fluid Mech.

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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 gascomposition 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 liquidspecific 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-planeaverage 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 ...

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“…There are several papers and reports dealing with droplet evaporation (e.g. [1][2][3][4][5]). Fuels are usually characterized by a single surrogate component for most of the evaporation models implemented in computational fluid dynamic codes since these models are computationally inexpensive.…”

Section: Introductionmentioning

confidence: 99%

Modelling of evaporation and dissolution of multicomponent oil droplet in shallow water

Abianeh¹,

Chen²

2012

Advanced Computational Methods and Experiments in Heat Transfer XII

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A multicomponent evaporation and dissolution model was applied to study the dynamics of the mass transfer of dispersed oil in shallow waters. This model, in Lagrangian form, was coupled with the Princeton Ocean Circulation model (POM) for simulating oil droplet dispersion in an oceanic environment. The oil dispersion was modeled for a standard sea-mount shallow water environment. The most abundant petroleum hydrocarbons in the hydrocarbon-enriched of oil plum larger than C 1 -C 5 were benzene, toluene, ethylbenzene, and total xylenes. Therefore, the oil surrogate, which consists of these components, is studied. The liquid-liquid equilibrium and vapor-liquid equilibrium equations are solved for evaluating the droplet life time. A rapid mixing model is used by reason of the shorter internal mass diffusion time scale in comparison to the droplet life time. Four different droplet sizes, 1.5, 1, 0.5, and 0.1mm, are considered in this study. The droplet with a diameter of 1mm has a shorter life time in this specific environment.

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Modeling of Multicomponent Fuels Using Continuous Distributions with Application to Droplet Evaporation and Sprays

Cited by 106 publications

References 23 publications

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

Direct numerical simulation of a transitional temporal mixing layer laden with multicomponent-fuel evaporating drops using continuous thermodynamics

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

Modelling of evaporation and dissolution of multicomponent oil droplet in shallow water

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