A study of the influence of exhaust gas recirculation and stoichiometry on the heat release in the end-gas prior to knock using rotational coherent anti-Stokes-Raman spectroscopy thermometry

Grandin, Börje; Denbratt, Ingemar; Bood, Joakim; Brackmann, Christian; Bengtsson, Per-Erik

doi:10.1243/146808702762230914

Cited by 14 publications

(6 citation statements)

References 20 publications

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“…They demonstrated the first rotational CARS experiments in a natural gas fired spark-ignited IC engine. In their follow-up work they studied also the influences of mixture composition and exhaust gas recirculation (EGR) on the knock behaviour [289]. A summary of these activities has been given by Brackmann et al [290].…”

Section: Multi-species and Multiplex Measurementsmentioning

confidence: 99%

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

129

112

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Laser-based methods have transformed combustion diagnostics in the past few decades. The high intensity, coherence, high spectral resolution and frequency tunability available from laser radiation has provided powerful tools for studying microscopic processes and macroscopic phenomena in combustion by linear and nonlinear optical processes. This review focuses on nonlinear optical techniques based on resonant four-wave mixing for non-intrusive measurements of minor species in combustion. The importance of minor species such as reaction intermediates is outlined together with the challenges they present for detection and measurement in the hostile environments of flames, technical combustors, and engines. The limitations of conventional optical methods for such measurements are described and the particular advantages of coherent methods using nonlinear optical techniques are discussed.The basic physics underlying four-wave wave mixing processes and theoretical models for signal calculation are then presented together with a discussion of how combustion parameters may be derived from analysis of signals generated in various four-wave mixing processes. The most important four-wave mixing processes, in this context, are then reviewed:Degenerate Four-Wave Mixing (DFWM), Coherent Anti-Stokes Raman Scattering (CARS), Laser Induced Grating Spectroscopy (LIGS) and Polarization Spectroscopy (PS). In each case the fundamental physics is outlined to explain the particular properties and diagnostic advantages of each technique. The application of the methods mentioned to molecular physics studies of combustion species is then reviewed along with their application in measurement of concentration, temperature and other combustion parameters. Related nonlinear techniques and recent extensions to the ultra-fast regime are briefly reviewed. Finally practical considerations relevant to multi-dimensional and multi-species measurements, as well as applications in technical combustion systems are discussed.Keywords: nonlinear optical spectroscopy, four-wave mixing, combustion diagnostics, minor species detection, laser-induced gratings, polarization spectroscopy IntroductionEnergy from renewable sources such as solar and wind power is the goal of much current research and technological development. Combustion, however, is and is likely to remain for the foreseeable future, the most important energy source for heat, electrical power and especially for transportation. In technical combustion systems the chemical energy of fossil fuels such as coal, crude oil and natural gas is converted into heat through oxidation with oxygen from air. However, fossil fuel resources are limited and alternatives like biofuels [1] or novel technologies such as fuel cells [2] are not yet able to meet the demand. Consequently, for a sustainable use of fossil fuels it is desirable to further improve the efficiency, maintainability and reliability of existing combustion devices. Achieving such improvements depends upon an improved understanding of t...

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Section: Multi-species and Multiplex Measurementsmentioning

confidence: 99%

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

129

112

View full text Add to dashboard Cite

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“…Moreover, the measured temperature profiles were in good agreement with calculated profiles using a detailed chemical mechanism for mixtures of iso-octane and n-heptane. In later measurements, an investigation was made of the thermal boundary layer close to the combustion chamber wall under knocking conditions [51][52][53]. The latest campaign was the most successful, and the results presented in this paper originate from this campaign if not otherwise stated.…”

Section: Dual-broadband Rotational Carsmentioning

confidence: 90%

“…This paper summarizes our experience of rotational CARS thermometry in engines, based on four measurement campaigns performed between 1995 and 2000. This work has led to a series of contributions in the SAE Paper series [50][51][52][53]. The focus has mainly been on how the rotational CARS temperatures evaluated are used to understand the combustion process together with data from pressure registrations and heat flux data, and generally the presentation of the DB-RCARS technique and its capabilities has been limited.…”

Section: Introductionmentioning

confidence: 99%

Thermometry in internal combustion engines via dual-broadband rotational coherent anti-Stokes Raman spectroscopy

Brackmann¹,

Bood²,

Afzelius³

et al. 2004

Meas. Sci. Technol.

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Rotational coherent anti-Stokes Raman spectroscopy (CARS) has since the beginning of the 1980s been developed as a non-intrusive tool for temperature measurements in combustion. Since the introduction of the dual-broadband concept in 1986, the quality of the technique has been much improved, and application to practical combustion situations facilitated. Since the first demonstration of its use in spark-ignition engines in 1993, several measurement campaigns in engines have been accomplished. These campaigns concerned temperature measurements in the unburned gas mixture before combustion as part of a larger project with the aim of improving the knowledge on the phenomenon of engine knock. In this paper, the results of this work are reviewed with a focus on the characteristics of the technique and the quality of the evaluated temperatures. Re-evaluations of data using an improved theoretical model are presented and compared with previous results. Moreover, the treatment of large data sets on single shots from spatial regions with conditions varying from unburned to burned gas is discussed. It is demonstrated that dual-broadband rotational CARS probing nitrogen and oxygen has a high potential for thermometry at the conditions in the unburned gas mixture. Merits and limitations of the technique are discussed and the issues treated are, among others, experimental problems, data evaluation, and single-shot temperature accuracy.

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“…9). According to a previous report using a production engine (14) , reducing the knock intensity causes a drop of the heat release peak and also a double-humped heat release curve. This means that the first hump is due to the flame propagation while the second one is due to the auto-ignition.…”

Section: Observation In Knock Conditionsmentioning

confidence: 95%

Analysis of Knock Phenomenon Induced in a Constant Volume Chamber by Local Gas Temperature Measurement and Visualization

Moriyoshi

Kobayashi

Enomoto³

2005

JSME international journal. Ser. B, Fluids and thermal engineer

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Knock phenomenon in SI engines is regarded as an auto-ignition of unburned end-gas, and it has been widely examined by using rapid compression machines (RCM), shock-tubes or test engines. Recent researches point out the importance of the low temperature chemical reaction and the negative temperature coefficient (NTC). To investigate the effects, analyses of instantaneous local gas temperature, flow visualization and gaseous pressure were conducted in this study. As measurements using real engines are too difficult to analyze, the authors aimed to make measurements using a constant volume vessel under knock conditions where propagating flame exists during the induction time of auto-ignition. Adopting the two-wire thermocouple method enabled us to measure the instantaneous local gas temperature until the moment when the flame front passes by. High-speed images inside the unburned region were also recorded simultaneously using an endoscope. As a result, it was found that when knock occurs, the auto-ignition initiation time seems slightly early compared to the results without knock. This causes a higher volume ratio of unburned mixture and existence of many hot spots and stochastically leads to an initiation of knock.

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A study of the influence of exhaust gas recirculation and stoichiometry on the heat release in the end-gas prior to knock using rotational coherent anti-Stokes-Raman spectroscopy thermometry

Cited by 14 publications

References 20 publications

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Thermometry in internal combustion engines via dual-broadband rotational coherent anti-Stokes Raman spectroscopy

Analysis of Knock Phenomenon Induced in a Constant Volume Chamber by Local Gas Temperature Measurement and Visualization

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