Large eddy simulation of auto-ignition kernel development of transient methane jet in hot co-flow

Knock and super-knock are abnormal combustion phenomena in engines, however, they are hard to study comprehensively through optical experimental methods due to their inherent destructive nature. In present work, the methodology of large eddy simulation (LES) coupled with G equations and a detailed mechanism of primary reference fuel (PRF) combustion is utilized to address the mechanisms of knock and super-knock phenomena in a downsized spark ignition gasoline engine. The knock and super-knock with pressure oscillation are qualitatively duplicated through present numerical models. As a result, the combustion and onset of autoignition is more likely to occur at top dead center (TDC), which causes end gas at a higher temperature and pressure. It is reasonable to conclude that the intensity of knock is not only proportional to the mass fraction of mixtures burned by the autoignition flame but the thermodynamics of the unburned end-gas mixture, and the effect of thermodynamics is more important. It also turns out that two auto-ignitions occur in conventional knock conditions, while only one auto-ignition takes place in super-knock conditions. However, the single autoignition couples with the pressure wave and they reinforce each other, which eventually evolves into detonation combustion. This work gives the valuable insights into knock phenomena in spark ignition gasoline engines.

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Large Eddy Simulation of a premixed jet flame stabilized by a vitiated co-flow: Evaluation of auto-ignition tabulated chemistry

Combustion and Flame ◽

10.1016/j.combustflame.2013.06.011 ◽

2013 ◽

Vol 160 (12) ◽

pp. 2879-2895 ◽

Cited By ~ 17

Author(s):

Christophe Duwig ◽

Matthew J. Dunn

Keyword(s):

Large Eddy Simulation ◽

Jet Flame ◽

Eddy Simulation ◽

Auto Ignition ◽

Tabulated Chemistry ◽

Large Eddy

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Large-eddy simulation of H2–air auto-ignition using tabulated detailed chemistry

Journal of Turbulence ◽

10.1080/14685240801953048 ◽

2008 ◽

Vol 9 ◽

pp. N13 ◽

Cited By ~ 12

Author(s):

J. Galpin ◽

C. Angelberger ◽

A. Naudin ◽

L. Vervisch

Keyword(s):

Large Eddy Simulation ◽

Detailed Chemistry ◽

Eddy Simulation ◽

Auto Ignition ◽

Large Eddy

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Investigation of auto-ignition in turbulent methanol spray flames using Large Eddy Simulation

Combustion and Flame ◽

10.1016/j.combustflame.2013.07.004 ◽

2013 ◽

Vol 160 (12) ◽

pp. 2941-2954 ◽

Cited By ~ 27

Author(s):

Vinayaka N. Prasad ◽

Assaad R. Masri ◽

Salvador Navarro-Martinez ◽

Kai H. Luo

Keyword(s):

Large Eddy Simulation ◽

Eddy Simulation ◽

Spray Flames ◽

Auto Ignition ◽

Large Eddy

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Large eddy simulations of diesel-fuel injection and auto-ignition at transcritical conditions

International Journal of Engine Research ◽

10.1177/1468087418819546 ◽

2018 ◽

Vol 20 (1) ◽

pp. 58-68 ◽

Cited By ~ 11

Author(s):

Matthias Ihme ◽

Peter C Ma ◽

Luis Bravo

Keyword(s):

Large Eddy Simulation ◽

Diesel Fuel ◽

Fuel Injection ◽

Large Eddy Simulations ◽

Diffuse Interface ◽

Modeling Framework ◽

Eddy Simulation ◽

Auto Ignition ◽

Large Eddy ◽

Diesel Fuel Injection

Large eddy simulations of transcritical injection and auto-ignition of n-dodecane in a combustion chamber are performed. To this end, a diffuse-interface method is employed that solves the compressible multi-species conservation equations, and a cubic state equation together with real-fluid transport properties is employed to describe the transcritical fluid state. The reaction chemistry is represented by a finite-rate chemistry model involving a 33-species reduced mechanism for n-dodecane. Compared to commonly employed two-phase approaches, the method presented in this work does not introduce tunable parameters for spray-breakup. Large eddy simulation calculations are performed by considering the Spray A single-hole injector at non-reacting and reacting conditions at a pressure of 60 bar and temperatures between 800 and 1200 K. Quantitative comparisons with measurements for liquid and vapor penetration lengths are performed for non-reacting conditions, and sensitivity to threshold values on mixture fraction are examined. The analysis of reacting flow simulations focuses on comparisons of the instantaneous temperature and species fields for OH and CH2O at 800 and 900 K, respectively. Quantitative comparisons with measurements for ignition delay and lift-off heights as a function of ambient temperature are performed. To examine the transient ignition phase, comparisons of radially integrated OH profiles obtained from the simulations with reported measurements for OH* are performed, showing good agreement. These results show that the large eddy simulation modeling framework adequately reproduces the corresponding ignition processes, which are relevant to realistic diesel-fuel injection systems.

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