A New Firing Concept for Internal Combustion Engines: “I'APIR”

Robinet, Cyril; Higelin, Pascal; Moreau, Bruno; Pajot, Olivier; Andrzejewski, J.

doi:10.4271/1999-01-0621

Cited by 52 publications

(13 citation statements)

References 17 publications

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“…1,2 A variety of systems have been proposed for ignition of lean premixed methane/air, for example, by means of Diesel pilots, 3–7 laser ignition, 8 as well as by turbulent jets issuing from scavenged or un-scavenged pre-chambers. 9–21 Among all these techniques, un-scavenged pre-chambers are particularly attractive due to their low cost and engineering simplicity.…”

Section: Introductionmentioning

confidence: 99%

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Wright

Schiliro

et al. 2018

International Journal of Engine Research

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Prechamber ignition technology receives increasing attention due to its considerable improvement on engine combustion efficiency and stability. However, fundamental knowledge concerning flame propagation inside the pre-chamber and jet formation in the main chamber is still quite scarce. In this study, a small (<0.5% VTDC) un-scavenged pre-chamber was tested in a medium size gas engine with pressure transducers installed in both pre- and main chamber. Three-dimensional computational reactive fluid dynamics Reynolds-averaged Navier–Stokes simulations were carried out using a level-set combustion model –G-equation – towards improved understanding of the combustion processes occurring inside the pre and main chamber. The characteristics of the turbulence and the flame at locations just ahead of the propagating turbulent flame front were recorded and analysed by means of the well-known Borghi–Peters diagram. The results revealed that the characteristics of the flame inside the pre-chamber differed greatly from those inside the main chamber due to considerably reduced turbulent length scales. In addition, a wide range of turbulence intensity and length scales are covered throughout the combustion event, presenting a significant challenge to modelling of flame–turbulence interaction. Various turbulent flame speed ( ST) closures widely used in internal combustion engine simulation were therefore assessed and the ranges of their respective model constants explored. A correlation for ST is subsequently proposed by blending two formulations of Gülder developed for small and large scale turbulence, respectively, and compared to the well-known Peters correlation. With appropriate model constants, both successfully reproduce the pre and main chamber combustion for the reference case in terms of evolutions of cylinder pressure, heat release rate and pressure difference between pre and main chamber. Following successful calibration of the reference operating condition, variations in engine speed, load, spark timing and lambda were calculated using both correlations, demonstrating encouraging predictive capabilities of the proposed modelling strategy.

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Section: Introductionmentioning

confidence: 99%

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Wright

Schiliro

et al. 2018

International Journal of Engine Research

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“…The implementation is carried out by first flagging, in each detector, subsets of data that have excess power, which we refer to as "events". This step is carried out with a time-frequency decomposition based on the Qtransform [34][35][36] that we will refer to as Omicron [37]. This first step is followed by a time coincidence of such excess power among the network of detectors.…”

Section: Arxiv:151105955v3 [Gr-qc] 2 Mar 2017mentioning

confidence: 99%

“…Omicron provides fast and accurate identification of statistically significant deviations from Gaussian noise in a single interferometer's data stream. It is based on the Q transform, which varies the duration of data used within a Fourier transform to maintain a constant quality factor Q ∝ τ · f 0 , meaning the duration τ is inversely proportional to the targeted frequency f 0 [34][35][36][37]. By repeatedly decomposing a data stream into several planes of constant Q, Omicron can search for excess power with different characteristic aspect ratios in the time-frequency plane.…”

Section: B Omicronmentioning

confidence: 99%

Information-theoretic approach to the gravitational-wave burst detection problem

et al. 2017

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The observational era of gravitational-wave astronomy began in the fall of 2015 with the detection of GW150914. One potential type of detectable gravitational wave is short-duration gravitational-wave bursts, whose waveforms can be difficult to predict. We present the framework for a detection algorithm for such burst events-oLIB-that can be used in low latency to identify gravitational-wave transients. This algorithm consists of (1) an excess-power event generator based on the Q transform-Omicron-, (2) coincidence of these events across a detector network, and (3) an analysis of the coincident events using a Markov chain Monte Carlo Bayesian evidence calculator-LALInferenceBurst. These steps compress the full data streams into a set of Bayes factors for each event. Through this process, we use elements from information theory to minimize the amount of information regarding the signal-versus-noise hypothesis that is lost. We optimally extract this information using a likelihood-ratio test to estimate a detection significance for each event. Using representative archival LIGO data across different burst waveform morphologies, we show that the algorithm can detect gravitational-wave burst events of astrophysical strength in realistic instrumental noise. We also demonstrate that the combination of Bayes factors by means of a likelihood-ratio test can improve the detection efficiency of a gravitational-wave burst search. Finally, we show that oLIB's performance is robust against the choice of gravitational-wave populations used to model the likelihood-ratio test likelihoods.

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“…This has necessitated the development of higherenergy ignition sources [7,8]. A pre-chamber combustor application is one such technology, having been researched extensively [9,10,11,12,13]. SI engines that utilize prechambers generally retain the spark plug but relocate it to the pre-chamber and repurpose it as the ignition source for the…”

Section: Introductionmentioning

confidence: 99%

Methodology for Combustion Analysis of a Spark Ignition Engine Incorporating a Pre-Chamber Combustor

Bunce

Blaxill

2014

SAE Technical Paper Series

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With an increasing global awareness of the need to conserve fuel resources and reduce carbon dioxide emissions, the automotive sector has been seeking gains in engine efficiency. One such method for achieving these gains on a spark ignition (SI) engine platform is through lean burn operation. Ultra-lean operation (λ>2) has demonstrated the ability to increase thermal efficiency and significantly reduce emissions of nitrogen oxides (NO x ) due primarily to lower mean gas temperatures. Turbulent Jet Ignition (TJI), a pre-chamberbased combustion system, is a technology that enables ultra-lean operation. TJI is also an effective knock mitigation system due to the distributed nature of main chamber ignition, resulting in rapid burn rates.Pre-chamber combustors such as that utilized in TJI have been studied extensively for decades, but the interaction of the combustion events between the two chambers is not well understood. Additionally, current in-cylinder pressure transducer-based combustion analysis is limited in its effectiveness at capturing TJI combustion characteristics, particularly start of combustion (SOC) in the main chamber. This can lead to misleading heat release results and incomplete understanding of ignition and chamber interaction. This study analyzes the limitations of current combustion analysis techniques to characterize TJI and proposes a new methodology for combustion analysis.An optical engine is used to qualitatively assess pre-chamber jet formation and the subsequent main chamber ignition events. This data is synthesized with that of a single cylinder metal engine counterpart providing empirical heat release information. Utilizing high speed pressure transducers in both pre-chamber and main chamber, the validity of heat release data is explored within the context of the optically observed combustion process. A computational fluid dynamics (CFD) model is employed as an explanatory tool for the pre-chamber combustion event and the gas exchange process between the chambers. Informed by qualitative optical engine data, empirical heat release data, and CFD, this study seeks to produce a new methodology for combustion analysis that is applicable not only to TJI but to most pre-chamber-based SI combustion systems. Further accurate understanding of the interaction of the combustion events between the chambers and the gas exchange process can lead to optimum prechamber design and operation, and enable system scalability.

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A New Firing Concept for Internal Combustion Engines: “I'APIR”

Cited by 52 publications

References 17 publications

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

Information-theoretic approach to the gravitational-wave burst detection problem

Methodology for Combustion Analysis of a Spark Ignition Engine Incorporating a Pre-Chamber Combustor

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