Large-eddy simulation of dual-fuel spray ignition at different ambient temperatures

Tekgül, Bulut; Kahila, Heikki; Kaario, Ossi; Vuorinen, Ville

doi:10.1016/j.combustflame.2020.01.017

Cited by 53 publications

(66 citation statements)

References 63 publications

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“…In the present study, Navier-Stokes equations for gas phase compressible turbulent flow are solved using the LES approach. The present numerical strategy has been thoroughly validated in our previous publications for the SF ECN Spray A case 17,[36][37][38] and SF/DF cases 2,3 . The solver provides results in a very good agreement with the ECN data in terms of the liquid length, vapor penetration, radial mixture fraction profiles, and ignition characteristics.…”

Section: Numerical Methodologymentioning

confidence: 99%

“…In this respect, there have been considerable improvements in engine technologies such as the utilization of renewable fuels, electrification, and development of hybrid engines. Recently, in the context of compression ignition (CI) engines, more advanced combustion strategies such as dual-fuel (DF) combustion have been proposed and used as viable solutions to provide higher efficiency and lower emissions compared to the conventional CI engines [1][2][3][4][5] . The idea of DF combustion in CI engines is to burn one (or a combination of) low reactivity fuel(s) (LRF), such as methane, with the assistance of a high reactivity fuel (HRF), such as diesel.…”

Section: Introductionmentioning

confidence: 99%

“…The idea of DF combustion in CI engines is to burn one (or a combination of) low reactivity fuel(s) (LRF), such as methane, with the assistance of a high reactivity fuel (HRF), such as diesel. With relevance to this study, pilot HRF is injected to the lean mixture of premixed LRF/air to initiate ignition and burn interactively with LRF [1][2][3][6][7][8][9][10][11] . Typically, diesel is injected in small amounts to avoid high emissions, however, it should release sufficient energy to ignite the LRF under desired conditions.…”

Section: Introductionmentioning

confidence: 99%

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Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two n-dodecane mechanisms at different ambient temperatures

Kannan

Gadalla

Tekgül

et al. 2020

International Journal of Engine Research

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In dual-fuel compression ignition engines, a high-reactivity fuel, such as diesel, is directly injected to the engine cylinder to ignite a mixture of low-reactivity fuel and air. This study targets improving the general understanding on the dual-fuel ignition phenomenon using zero-dimensional homogeneous reactor studies and three-dimensional large eddy simulation together with finite-rate chemistry. Using the large eddy simulation framework, n-dodecane liquid spray is injected into the lean ambient methane–air mixture at [Formula: see text]. The injection conditions have a close relevance to the Engine Combustion Network Spray A setup. Here, we assess the effect of two different chemical mechanisms on ignition characteristics: a skeletal mechanism with 54 species and 269 reaction steps (Yao mechanism) and a reduced mechanism with 96 species and 993 reaction steps (Polimi mechanism). Altogether three ambient temperatures are considered: 900, 950, and 1000 K. Longer ignition delay time is observed in three-dimensional large eddy simulation spray cases compared to zero-dimensional homogeneous reactors, due to the time needed for fuel mixing in three-dimensional large eddy simulation sprays. Although ignition is advanced with the higher ambient temperature using both chemical mechanisms, the ignition process is faster with the Polimi mechanism compared to the Yao mechanism. The reasons for differences in ignition timing with the two mechanisms are discussed using the zero-dimensional and three-dimensional large eddy simulation data. Finally, heat release modes are compared in three-dimensional large eddy simulation according to low- and high-temperature chemistry in dual-fuel combustion at different ambient temperatures. It is found that Yao mechanism overpredicts the first-stage ignition compared to Polimi mechanism, which leads to the delayed second-stage ignition in Yao cases compared to Polimi cases. However, the differences in dual-fuel ignition for Polimi and Yao mechanisms are relatively smaller at higher ambient temperatures.

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Section: Numerical Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two n-dodecane mechanisms at different ambient temperatures

Kannan

Gadalla

Tekgül

et al. 2020

International Journal of Engine Research

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“…However, in the present implicit model, such a dissipative contribution is implicitly introduced and it is controlled locally by choosing a dissipative numerical scheme for discretization of convection terms. Following the previous works on spray A [34,[53][54][55][56][57], ILES is implemented through a non-linear flux limiter termed as Gamma scheme [79].…”

Section: Implicit Modelmentioning

confidence: 99%

“…Under reacting conditions, various works employed different combustion models along with the LES/LPT approach to investigate ignition-related phenomena such as flame structure and stabilization [44][45][46][47][48][49][50], radiative heat transfer [51], as well as ignition modes and dynamics [52]. Additionally in [53][54][55][56][57], the cylindrical injection volume filtering concept was utilized together with the KHRT and ILES models, as discussed in [34].…”

Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulation of ECN Spray A: Sensitivity Study on Modeling Assumptions

et al. 2020

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In this study, various mixing and evaporation modeling assumptions typically considered for large-eddy simulation (LES) of the well-established Engine Combustion Network (ECN) Spray A are explored. A coupling between LES and Lagrangian particle tracking (LPT) is employed to simulate liquid n-dodecane spray injection into hot inert gaseous environment, wherein Lagrangian droplets are introduced from a small cylindrical injection volume while larger length scales within the nozzle diameter are resolved. This LES/LPT approach involves various modeling assumptions concerning the unresolved near-nozzle region, droplet breakup, and LES subgrid scales (SGS) in which their impact on common spray metrics is usually left unexplored despite frequent utilization. Here, multi-parametric analysis is performed on the effects of (i) cylindrical injection volume dimensions, (ii) secondary breakup model, particularly Kelvin–Helmholtz Rayleigh–Taylor (KHRT) against a no-breakup model approach, and (iii) LES SGS models, particularly Smagorinsky and one-equation models against implicit LES. The analysis indicates the following findings: (i) global spray characteristics are sensitive to radial dimension of the cylindrical injection volume, (ii) the no-breakup model approach performs equally well, in terms of spray penetration and mixture formation, compared with KHRT, and (iii) the no-breakup model is generally insensitive to the chosen SGS model for the utilized grid resolution.

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Studies on theory and modeling of droplet and spray combustion in China: a review

Zhou

2021

Acta Mech. Sin.

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Large-eddy simulation of dual-fuel spray ignition at different ambient temperatures

Cited by 53 publications

References 63 publications

Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two n-dodecane mechanisms at different ambient temperatures

Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two n-dodecane mechanisms at different ambient temperatures

Large-Eddy Simulation of ECN Spray A: Sensitivity Study on Modeling Assumptions

Studies on theory and modeling of droplet and spray combustion in China: a review

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