A large-eddy simulation study on the influence of diesel pilot spray quantity on methane-air flame initiation

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A large-eddy simulation study on the influence of diesel pilot spray quantity on methane-air flame initiation. / Kahila, H.; Kaario, O.; Ahmad, Z.; Ghaderi Masouleh, M.; Tekgül, B.; Larmi, M.; Vuorinen, V.

julkaisussa: Combustion and Flame, Vuosikerta 206, 30.05.2019, s. 506-521.

Tutkimustuotos: Lehtiartikkelivertaisarvioitu

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Bibtex - Lataa

@article{f921a59baea649ae9d6da0b64ebccb04,
title = "A large-eddy simulation study on the influence of diesel pilot spray quantity on methane-air flame initiation",
abstract = "The present study is a continuation of the previous work by Kahila et al. (2019), in which a dual-fuel (DF) ignition process was numerically investigated by modeling liquid diesel-surrogate injection into a lean methane-air mixture in engine relevant conditions. Earlier, the injection duration (tinj) of diesel-surrogate exceeded substantially the characteristic autoignition time scale. Here, such a pilot spray ignition problem is studied at a fixed mass flow rate but with a varying tinj. The focus is on understanding the influence of pilot quantity on spray dilution process and low- and high-temperature chemistry. In total, ten cases are computed with multiple diesel pilot quantities by utilizing a newly developed large-eddy simulation/finite-rate chemistry solver. The baseline spray setup corresponds to the Engine Combustion Network (ECN) Spray A configuration, enabling an extensive validation of the present numerical models and providing a reference case for the DF computations. Additionally, experimental results from a single-cylinder laboratory engine are provided to discuss the ignition characteristics in the context of a real application. The main results of the present study are: (1) reducing tinj introduces excessive dilution of the DF mixture, (2) dilution lowers the reactivity of the DF mixture, leading to delayed high-temperature ignition and slow overall methane consumption, (3) low enough pilot quantity (tinj < 0.3 ms) may lead to very long ignition delay times, (4) cumulative heat release is dominated by low/high-temperature chemistry at low/high tinj values, (5) analysis of the underlying chemistry manifold implies that the sensitivity of ignition chemistry on mixing is time-dependent and connected to the end of injection time, and 6) long ignition delay times at very low tinj values can be decreased by decreasing injection pressure.",
keywords = "Dual-fuel, ECN, Ignition, LES, Pilot, Spray A",
author = "H. Kahila and O. Kaario and Z. Ahmad and {Ghaderi Masouleh}, M. and B. Tekg{\"u}l and M. Larmi and V. Vuorinen",
year = "2019",
month = "5",
day = "30",
doi = "10.1016/j.combustflame.2019.05.025",
language = "English",
volume = "206",
pages = "506--521",
journal = "Combustion and Flame",
issn = "0010-2180",

}

RIS - Lataa

TY - JOUR

T1 - A large-eddy simulation study on the influence of diesel pilot spray quantity on methane-air flame initiation

AU - Kahila, H.

AU - Kaario, O.

AU - Ahmad, Z.

AU - Ghaderi Masouleh, M.

AU - Tekgül, B.

AU - Larmi, M.

AU - Vuorinen, V.

PY - 2019/5/30

Y1 - 2019/5/30

N2 - The present study is a continuation of the previous work by Kahila et al. (2019), in which a dual-fuel (DF) ignition process was numerically investigated by modeling liquid diesel-surrogate injection into a lean methane-air mixture in engine relevant conditions. Earlier, the injection duration (tinj) of diesel-surrogate exceeded substantially the characteristic autoignition time scale. Here, such a pilot spray ignition problem is studied at a fixed mass flow rate but with a varying tinj. The focus is on understanding the influence of pilot quantity on spray dilution process and low- and high-temperature chemistry. In total, ten cases are computed with multiple diesel pilot quantities by utilizing a newly developed large-eddy simulation/finite-rate chemistry solver. The baseline spray setup corresponds to the Engine Combustion Network (ECN) Spray A configuration, enabling an extensive validation of the present numerical models and providing a reference case for the DF computations. Additionally, experimental results from a single-cylinder laboratory engine are provided to discuss the ignition characteristics in the context of a real application. The main results of the present study are: (1) reducing tinj introduces excessive dilution of the DF mixture, (2) dilution lowers the reactivity of the DF mixture, leading to delayed high-temperature ignition and slow overall methane consumption, (3) low enough pilot quantity (tinj < 0.3 ms) may lead to very long ignition delay times, (4) cumulative heat release is dominated by low/high-temperature chemistry at low/high tinj values, (5) analysis of the underlying chemistry manifold implies that the sensitivity of ignition chemistry on mixing is time-dependent and connected to the end of injection time, and 6) long ignition delay times at very low tinj values can be decreased by decreasing injection pressure.

AB - The present study is a continuation of the previous work by Kahila et al. (2019), in which a dual-fuel (DF) ignition process was numerically investigated by modeling liquid diesel-surrogate injection into a lean methane-air mixture in engine relevant conditions. Earlier, the injection duration (tinj) of diesel-surrogate exceeded substantially the characteristic autoignition time scale. Here, such a pilot spray ignition problem is studied at a fixed mass flow rate but with a varying tinj. The focus is on understanding the influence of pilot quantity on spray dilution process and low- and high-temperature chemistry. In total, ten cases are computed with multiple diesel pilot quantities by utilizing a newly developed large-eddy simulation/finite-rate chemistry solver. The baseline spray setup corresponds to the Engine Combustion Network (ECN) Spray A configuration, enabling an extensive validation of the present numerical models and providing a reference case for the DF computations. Additionally, experimental results from a single-cylinder laboratory engine are provided to discuss the ignition characteristics in the context of a real application. The main results of the present study are: (1) reducing tinj introduces excessive dilution of the DF mixture, (2) dilution lowers the reactivity of the DF mixture, leading to delayed high-temperature ignition and slow overall methane consumption, (3) low enough pilot quantity (tinj < 0.3 ms) may lead to very long ignition delay times, (4) cumulative heat release is dominated by low/high-temperature chemistry at low/high tinj values, (5) analysis of the underlying chemistry manifold implies that the sensitivity of ignition chemistry on mixing is time-dependent and connected to the end of injection time, and 6) long ignition delay times at very low tinj values can be decreased by decreasing injection pressure.

KW - Dual-fuel

KW - ECN

KW - Ignition

KW - LES

KW - Pilot

KW - Spray A

UR - http://www.scopus.com/inward/record.url?scp=85066280769&partnerID=8YFLogxK

U2 - 10.1016/j.combustflame.2019.05.025

DO - 10.1016/j.combustflame.2019.05.025

M3 - Article

AN - SCOPUS:85066280769

VL - 206

SP - 506

EP - 521

JO - Combustion and Flame

JF - Combustion and Flame

SN - 0010-2180

ER -

ID: 34642412