Conditions In Which Vaporizing Fuel Drops Reach A Critical State In A Diesel Engine

Abraham, John; Givler, Shawn

doi:10.4271/1999-01-0511

Cited by 10 publications

(8 citation statements)

References 6 publications

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“…In the context of the discussion about atomization and vaporization, it is important to point out that it has recently been suggested that there may be no liquid phase at all because the pressure and the temperature in the chamber are supercritical relative to the fuel properties, 28 although earlier work had suggested that supercritical conditions are achieved only if the reduced pressure and temperature are about two. 187, 188 This recent suggestion that the liquid does not exist needs further study. It goes against what is generally believed about diesel sprays, but such ‘provocative’ suggestions need to be carefully considered and evaluated.…”

Section: Discussionmentioning

confidence: 98%

Critical observations on the modeling of nonreacting and reacting diesel sprays

Abraham

2015

Proceedings of the Institution of Mechanical Engineers, Part D:

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This paper begins by discussing the structure of nonreacting and reacting diesel sprays. After a general discussion of approaches to model nonreacting diesel sprays, results from some recent work employing the Reynolds-averaged Navier–Stokes equations to model the nonreacting spray are presented. It is shown through detailed comparison with measured results that, under conventional high-pressure, high-temperature chamber and high-pressure injection conditions, the vaporizing diesel spray behaves like a gas jet and can be modeled as such without noticeable loss of accuracy in reproducing the structure of the spray. Moving on to consider a reacting diesel spray, turbulence–chemistry interaction models for the reacting spray are reviewed. Challenges in determining the suitability of one model over another, based on information available in the literature, are highlighted. The Reynolds-averaged Navier–Stokes simulation results of reacting diesel sprays in which an unsteady-flamelet-generated manifold model is employed for turbulence–chemistry interactions are discussed in detail. It is shown that the model, like others reported in the literature, can predict the ignition delay and the flame lift-off heights with reasonable accuracy. The model has also been extended to compute the concentrations of soot and nitrogen oxides in reacting diesel sprays. Nitrogen oxides are modeled using the mechanism from GRI-Mech 3.0 and soot is modeled using a kinetic mechanism coupled with a tracer particle approach to estimate the residence times within the jet. As part of this review, other recent studies on modeling pollutants in the reacting diesel spray are also reviewed in this work. Finally, recent studies employing large-eddy simulations of diesel sprays are reviewed. Initial simulations of the reacting diesel spray using a large-eddy simulation approach coupled with an unsteady-flamelet-generated manifold model are presented. The paper closes with a summary and suggestions for further work in modeling diesel sprays.

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Section: Discussionmentioning

confidence: 98%

Critical observations on the modeling of nonreacting and reacting diesel sprays

Abraham

2015

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…This may again be related to differences in the mass diffusion rates of the two species, as explained in the previous paragraph, leading to more effective droplet heating in the case of the carbon dioxide ambient gas. Now, we ask the question: Do multidimensional vaporizing spray models that are in widespread use today [6][7] reproduce the trends identified above? In today's production Diesel engines, it may appear unlikely that the compression temperatures reach the values that should result in the droplet reaching the critical point.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…Studies are carried out with a detailed one-dimensional droplet vaporization model and a simplified droplet vaporization model as employed in multidimensional models [5][6][7] to obtain the results shown here and arrive at the conclusions.…”

Section: The Computational Modelmentioning

confidence: 99%

“…The properties (pD) , fi g ,X g are evaluated at a mean temperature, f, obtained using the 2/3 law [6,11].…”

Section: Simplified Droplet Vaporization Modelmentioning

confidence: 99%

“…In the simplified droplet vaporization model, the rate of change of mass of the droplet is given by the Frossling correlation [6][7][8].…”

Section: Simplified Droplet Vaporization Modelmentioning

confidence: 99%

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