Modeling Fuel Spray Auto-ignition using the FGM Approach: Effect of Tabulation Method

Egüz, U Ulas; Ayyapureddi, S Sridhar; Bekdemir, C Cemil; Somers, Lmt Bart; Goey, de Lph Philip

doi:10.4271/2012-01-0157

Cited by 11 publications

(6 citation statements)

References 21 publications

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“…It is clear that the LOL for the 0D FGM case (LOL=12.84 mm) is much shorter than that predicted by the 1D FGM case (LOL=18.34 mm), which follows the same trend of IDT observations discussed earlier. A similar trend was also found by Eguz et al [10] while studying tabulation methods for "Spray A" where LOL is found to have an almost linear correlation with the IDT. The reasons for this can be explained by the higher production of the progress variable in the near nozzle region caused by early ignition in the 0D FGM.…”

Section: Comparing 0d Fgm and 1d Fgm Simulationssupporting

confidence: 83%

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

Fang¹,

Ismail²,

Davy³

2019

SAE Technical Paper Series

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Combustion recession, an end of injection (EOI) diesel spray phenomenon, has been found to be a robust correlation parameter for UHC in diesel LTC strategies. Previous studies have shown that the likelihood of capturing combustion recession in numerical simulations is highly dependent on the details of the low-temperature chemistry reaction mechanisms employed. This study aims to further the understanding of the effects of different chemical mechanisms in the prediction of a reactive diesel spray and its EOI process: combustion recession. Studies were performed under the Engine Combustion Network's (ECN) "Spray A" conditions using the Reynolds-Averaged Navier-Stokes simulation (RANS) and the Flamelet Generated Manifold (FGM) combustion model with four different chemical mechanisms for n-dodecane that are commonly used in the engine simulation communitiesincluding recently developed reduced chemistry mechanisms. The flamelet database for each of the chemical mechanism is generated using two methods: 0D homogeneous reactor (HR) ignition flamelets and 1D igniting counterflow diffusion (ICDF) flamelets. The effect of different tabulation approaches is investigated first following by the discussion of the impact of chemical mechanisms on the prediction of combustion recession. Further discussions include an evaluation of the performance of chemical mechanisms in predicting the most relevant reacting spray characteristics compared to the ECN experimental database: ignition delay time (IDT), flame lift-off length (LOL) and flame reactive region. Results show that the choice of both tabulation method and chemical mechanism play a significant role in initial flame stabilization and end of injection (EOI) transient processes. In general, both tabulation techniques were able to qualitatively capture the flame characteristics before EOI, however ICDF tabulation is better suited for the FGM approach in order to capture combustion recession. Furthermore, the chemical mechanisms studied indicate that mechanisms with stronger low temperature chemistry predictions are more likely to promote combustion recession under an FGM framework.

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Section: Comparing 0d Fgm and 1d Fgm Simulationssupporting

confidence: 83%

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

Fang¹,

Ismail²,

Davy³

2019

SAE Technical Paper Series

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“…In previous studies, such value was generally found close to the LOL. 38,39 The baseline condition (O 2 = 15%, T = 900 K and r amb = 22:8 kg=m 3 ) was first considered to analyze ADF and FGM results. In particular, Figure 6 compares the computed heat release rate (RoHR) with the apparent experimental value.…”

Section: Experimental Validationmentioning

confidence: 99%

Modeling diesel combustion with tabulated kinetics and different flame structure assumptions based on flamelet approach

Lucchini

Pontoni

Somers³

2019

International Journal of Engine Research

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Computational fluid dynamics analysis represents a useful approach to design and develop new engine concepts and investigate advanced combustion modes. Large chemical mechanisms are required for a correct description of the combustion process, especially for the prediction of pollutant emissions. Tabulated chemistry models allow to reduce significantly the computational cost, maintaining a good accuracy. In the present work, an investigation of tabulated approaches, based on flamelet assumptions, is carried out to simulate turbulent Diesel combustion in the Spray A framework. The Approximated Diffusion Flamelet is tested under different ambient conditions and compared with Flamelet Generated Manifold, and both models are validated with Engine Combustion Network experimental data. Flame structure, combustion process and soot formation were analyzed in this work. Computed results confirm the impact of the turbulent–chemistry interaction on the ignition event. Therefore, a new look-up table concept Five-Dimensional-Flamelet Generated Manifold, that accounts for an additional dimension (strain rate), has been developed and tested, giving promising results.

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“…The implementation was, however, achieved by tabulating the reaction source terms in a library as a function of the mixture fraction Z , the scalar dissipation rate χ and the reaction progress variable C , estimated at the stoichiometric mixture fraction. Implementations such as this are sometimes referred to as flamelet-generated manifold methods 152–154 and so the implementation of Bajaj et al can be referred to as an unsteady-flamelet-generated manifold (UFGM) method. This model was employed to obtain the results of Table 3 (shown earlier) for the ignition delay.…”

Section: Predictive Capability Of Multidimensional Spray Modelsmentioning

confidence: 99%

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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Modeling Fuel Spray Auto-ignition using the FGM Approach: Effect of Tabulation Method

Cited by 11 publications

References 21 publications

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

A Study on Kinetic Mechanisms of Diesel Fuel Surrogate n-Dodecane for the Simulation of Combustion Recession

Modeling diesel combustion with tabulated kinetics and different flame structure assumptions based on flamelet approach

Critical observations on the modeling of nonreacting and reacting diesel sprays

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