Numerical analysis of knock during HCCI in a high compression ratio methanol engine based on LES with detailed chemical kinetics

Zhen, Xudong; Wang, Yang

doi:10.1016/j.enconman.2015.02.053

Cited by 61 publications

(8 citation statements)

References 39 publications

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“…The simulations are performed using the Li mechanism [35] in accordance with the 1D flame simulation. This mechanism has been widely used in LES [39,40] and more experimental validations have been done by Li et al [35]. Thus, the validation of the adopted mechanism shows its applicability in this work.…”

Section: Computation Detailsmentioning

confidence: 59%

Characterization of Distributed Combustion of Reformed Methanol Blends in a Model Gas Turbine Combustor

Shen¹,

Zhang²,

Zhang³

et al. 2022

SSRN Journal

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Section: Computation Detailsmentioning

confidence: 59%

Characterization of Distributed Combustion of Reformed Methanol Blends in a Model Gas Turbine Combustor

Shen¹,

Zhang²,

Zhang³

et al. 2022

SSRN Journal

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“…Pressure oscillation mechanism in high-load HCCI combustion has been extensively studied in the literature, [20][21][22][23][24][25][26][27][28] and a variety of methods of controlling the pressure oscillation have been suggested so far. They include fuel compositional stratification, [29][30][31][32][33][34] thermal stratification, 30,[35][36][37][38] variable injection timing, 22,39,40 alternative fuels with different octane numbers, 14,41,42 variable valve timing, 22,[43][44][45] variable residual gas ratios, 46,47 variable compression ratios, [48][49][50][51] variable intake air temperatures, [52][53][54] variable EGR ratios, 49,55,56 direct water injection, [57][58][59] etc.…”

Section: Introductionmentioning

confidence: 99%

Reducing pressure oscillation in high-load HCCI combustion via air injection before compression

Kobayashi

Nozaki

Hayashi

et al. 2021

International Journal of Engine Research

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Pressure oscillation often occurs in high-load homogeneous charge compression ignition (HCCI) combustion, which is a challenge in the development of HCCI engines for automobiles. This work proposes a novel method of reducing the pressure oscillation in HCCI combustion at high loads. The proposed technique injects air into homogeneous mixtures before compression, thereby giving local fuel concentration gradient. The fuel concentration gradient is expected to suppress a rapid pressure rise, resulting in reduced pressure oscillation. High-load HCCI combustion was simulated via a rapid compression machine with a high compression ratio. Varying the period from air injection to compression, that is, the waiting time, controlled the magnitude of fuel concentration gradient. The pressure oscillation was quantified and evaluated via the knock intensity (KI) and the averaged pressure rise rate. For the short waiting time; in other words, when the local fuel concentration gradient was large, the KI was very lower than that for no air injection. The KI, however, increased with the waiting time to approach that for no air injection. The oscillation modes were also different with and without air injection according to a modal analysis. The in-cylinder temperature distribution was visualized via the infrared radiometry to better understand the effect of air injection. For no air injection, the temperature in the cylinder uniformly increased, and the whole mixtures were ignited instantaneously. With air injection and for the short waiting time, on the other hand, hot spots developed on the rim of the injected air where the specific heat ratio was higher and then gradually spread throughout the chamber. Therefore, retarded auto-ignition and subsequently slow spread would limit a rapid pressure rise, resulting in reduced pressure oscillation in HCCI combustion. In conclusion, the proposed technique is effective for reducing the pressure oscillation in high-load HCCI combustion only for the short waiting time.

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“…Experimental studies require considerable resources and are costly, therefore they are not extensively used for the evaluation of the engine settings effect on knocking early in the engine design phase. In this respect, a more cost-effective method to predict the knocking onset is by using simulation methods [2], which can be generally classified into three categories: (1) detailed chemical kinetic mechanisms for the pre-flame (or low-temperature) reactions [31,32]; (2) simplified chemical kinetic mechanisms for the pre-flame reactions [33][34][35]; (3) empirical formulas based on Arrhenius expression [36].…”

Section: Introductionmentioning

confidence: 99%

“…Detailed chemical kinetic mechanisms [31,32] usually consider hundreds of species and thousands of elemental reactions, which provides the most detailed prediction of the local thermodynamic parameters including temperature, pressure and species concentration as well as the knocking onset. Nevertheless, this comes at the expense of huge computational cost, thus rendering this method not applicable in multi-variables and multi-objective optimisation studies based on engine cycle simulations [2].…”

Section: Introductionmentioning

confidence: 99%

Parametric Knocking Performance Investigation of Spark Ignition Natural Gas Engines and Dual Fuel Engines

Xiang

Theotokatos

Cui

et al. 2020

JMSE

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Both spark ignition (SI) natural gas engines and compression ignition (CI) dual fuel (DF) engines suffer from knocking when the unburnt mixture ignites spontaneously prior to the flame front arrival. In this study, a parametric investigation is performed on the knocking performance of these two engine types by using the GT-Power software. An SI natural gas engine and a DF engine are modelled by employing a two-zone zero-dimensional combustion model, which uses Wiebe function to determine the combustion rate and provides adequate prediction of the unburnt zone temperature, which is crucial for the knocking prediction. The developed models are validated against experimentally measured parameters and are subsequently used for performing parametric investigations. The derived results are analysed to quantify the effect of the compression ratio, air-fuel equivalence ratio and ignition timing on both engines as well as the effect of pilot fuel energy proportion on the DF engine. The results demonstrate that the compression ratio of the investigated SI and DF engines must be limited to 11 and 16.5, respectively, for avoiding knocking occurrence. The ignition timing for the SI and the DF engines must be controlled after −38°CA and 3°CA, respectively. A higher pilot fuel energy proportion between 5% and 15% results in increasing the knocking tendency and intensity for the DF Engine at high loads. This study results in better insights on the impacts of the investigated engine design and operating settings for natural gas (NG)-fuelled engines, thus it can provide useful support for obtaining the optimal settings targeting a desired combustion behaviour and engine performance while attenuating the knocking tendency.

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Numerical analysis of knock during HCCI in a high compression ratio methanol engine based on LES with detailed chemical kinetics

Cited by 61 publications

References 39 publications

Characterization of Distributed Combustion of Reformed Methanol Blends in a Model Gas Turbine Combustor

Characterization of Distributed Combustion of Reformed Methanol Blends in a Model Gas Turbine Combustor

Reducing pressure oscillation in high-load HCCI combustion via air injection before compression

Parametric Knocking Performance Investigation of Spark Ignition Natural Gas Engines and Dual Fuel Engines

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