Numerical analysis of knock combustion with methanol-isooctane blends in downsized SI engine

Han, Feng; Wei, Jianan; Zhang, Jing

doi:10.1016/j.fuel.2018.09.026

Cited by 33 publications

(12 citation statements)

References 24 publications

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“…Alcohol-containing fuels, such as methanol, have drawn attention of engine researchers in recent years mainly due to their renewability, wide source of availability, and high octane number, hence, knock mitigation [4,5] . Moreover, their cooling effect -due to their higher heat of vaporization compared to natural gas and gasoline -can reduce the charge peak combustion temperature which leads to NOx emission reduction [4,6] .…”

Section: Introductionmentioning

confidence: 99%

A numerical study on combustion mode characterization for locally stratified dual-fuel mixtures

Karimkashi

Kahila

Kaario

et al. 2020

Combustion and Flame

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a b s t r a c tCombustion modes in locally stratified dual-fuel (DF) mixtures are numerically investigated for methanol/n-dodecane blends under engine-relevant pressures. In the studied constant-volume numerical setup, methanol acts as a background low-reactivity fuel (LRF) while n-dodecane serves as high-reactivity fuel (HRF), controlling local ignition delay time. The spatial distribution of n-dodecane is modeled as a sinusoidal function parametrized by stratification amplitude ( Y ) and wavelength (0.01 mm <λ< 15 mm). In contrast, methanol is assumed to be fully premixed with air at equivalence ratio 0.8. First, onedimensional setup is investigated by hundreds of chemical kinetics simulations in ( Y , λ) parameter space. Further, the concepts by Sankaran et al. (2005, Proceedings of the Combustion Institute ) and Zeldovich (1980, Combustion and Flame ) on ignition front propagation speed are applied to develop a theoretical analysis of the time-dependent diffusion-reaction problem. The theoretical analysis predicts two combustion modes, (1) spontaneous ignition and (2) deflagrative propagation, and leads to an analytical expression for the border curve called β-curve herein. One-dimensional chemical kinetics simulations confirm the presence of two combustion modes in ( Y , λ) parameter space while the β-curve explains consistently the position of phase border observed in the simulations. Finally, the role of convective mixing is incorporated to the theoretical expression for the β-curve. The effect of convection on combustion modeis assessed by carrying out two-dimensional fully-resolved simulations with different turbulence levels. Two-dimensional numerical simulation results give evidence on combustion mode switching, which is consistent with predictions of the modified β-curve for turbulent cases. The practical output of the paper is the β-curve which is proposed as a predictive tool to estimate combustion modes for various fuels or fuel combinations.

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Section: Introductionmentioning

confidence: 99%

A numerical study on combustion mode characterization for locally stratified dual-fuel mixtures

Karimkashi

Kahila

Kaario

et al. 2020

Combustion and Flame

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“…A band-pass filter method was adopted to process the local pressures, and then maximum amplitude of pressure oscillations (MAPO) was determined as an index of knock intensity quantification. MAPO could be calculated with eq where θ 0 is the crank angle of calculation start, ε is the crank-angle window in which knock perhaps occurred, and p̂ stands for the filtered pressure.…”

Section: Methodologiesmentioning

confidence: 99%

Numerical Investigation on Knock Combustion in a Diesel–Dimethyl Ether Dual-Fuel Engine

et al. 2019

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Numerical investigation on knock was conducted in a direct-injection diesel engine with port premixed dimethyl ether (DME) fuel. Knock combustion at various engine operating conditions with a fixed speed was simulated, and the effects of premixed DME ratio, injection timing, and exhaust gas recirculation (EGR) rate on knock suppression were studied based on the multidimensional computational fluid dynamics (CFD) analysis. A reduced diesel–DME kinetic mechanism coupled with the CFD model was used to obtain local pressure and radical concentration at various monitoring locations within the computation domain. A method with a band-pass filter was then employed to deal with pressure data, and maximum amplitude of pressure oscillation was adopted as an evaluation index of the knock intensity. The analysis of species concentration was also used to quantify knock here. The research results indicated the profiles of pressure and major intermediate species could provide useful information to quantify and predict knock for DME–diesel dual-fuel premixed compression-ignition combustion. Moreover, using EGR was an effective way to reduce the knock intensity and delay the knock onset. A lower DME premixed ratio and retarded injection timing could also mitigate the knock.

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“…Minor knocks can promote combustion and improve the ITE of the engine, while severe knocks can worsen combustion. In this paper, the knock intensity (KI) is defined as the average of the maximum amplitude of pressure oscillations (MAPO) of the monitors 36 as follows where is the band-pass filtered pressure of the monitor i , θ 0 denotes the start crank angle of the filter windows, and w denotes the width of the filter window. A larger KI means more severe knock combustion.…”

Section: Numerical Model and Validationmentioning

confidence: 99%

Section: Initial Conditions Accurate Initial and Boundarymentioning

confidence: 99%

Effect of Hydrogen Blending on the Combustion Performance of a Gasoline Direct Injection Engine

Hong

et al. 2022

ACS Omega

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To explore the effect of hydrogen blending on the combustion of a gasoline direct injection engine, a three-dimensional model of the engine is built. The effects of some hydrogen volume fractions (HVFs) and ignition timings (ITs) on the engine performance parameters are studied. Furthermore, the microstructure and mechanism of combustion are analyzed. The simulation results reveal that when the gasoline engine is blended with hydrogen, the active hydroxyl radical concentration increases, and the combustion process is accelerated. When the IT is fixed, with the HVF rising, the peak heat release rate and cylinder pressure will increase. The ignition delay, combustion duration, and crank angle when cumulative heat release reaches 50% decrease. Additionally, the autoignition is shifted to an earlier time as the IT advances. Under the studied conditions with the increase in the HVF, the knock resistance is enhanced because hydrogen has a high knock resistance and octane number.

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Numerical analysis of knock combustion with methanol-isooctane blends in downsized SI engine

Cited by 33 publications

References 24 publications

A numerical study on combustion mode characterization for locally stratified dual-fuel mixtures

A numerical study on combustion mode characterization for locally stratified dual-fuel mixtures

Numerical Investigation on Knock Combustion in a Diesel–Dimethyl Ether Dual-Fuel Engine

Effect of Hydrogen Blending on the Combustion Performance of a Gasoline Direct Injection Engine

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