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Fuel Spray Tip Penetration Model for Double Injection Strategy

Université d'Orléans-Camille Hespel, Christine Mounaïm-Rousselle
École de Technologie Supérieure-Pascal Tetrault, Etienne Plamondon, Matthieu Breuze, Patrice Seers
Published 2015-04-14 by SAE International in United States
In this paper, a semi-empiric fuel spray tip penetration model is proposed. It is applied to single and double injection strategies taking into account the early and far field penetration. The model is based on the momentum flux as initially proposed by [1] for single injection but it is derived from mean mass flow rate herein. Fuel spray interaction with entrainment air is taken into account for the second injection. The proposed model is calibrated and validated using data from 9 experiments conducted with an indirect piezoelectric diesel injector under various injection strategies. The experiments included 1) injection rate measurements using the Bosch method to determine mean mass flow rate during injector opening as well as obtaining injection duration which are both entry parameters to the model; 2) Fuel spray tip penetrations were measured in a pressure vessel using high speed photography for single and double injection strategies. The experimental results were used to calibrate the model's constants and to verify the model's ability to predict spray behavior. Finally, the experimental results for some fuel…
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Thermodiffusive Effect on the Flame Development in Lean Burn Spark Ignition Engine

Total Marketing Services-Thomas Dubois
Universite D'Orleans-Pierre Brequigny, Fabien Halter, Christine Mounaïm-Rousselle, Bruno Moreau
Published 2014-10-13 by SAE International in United States
In Spark Ignition engines, the heat release rate is not only piloted by the mixture reactivity but also by its sensitivity to stretch effects. Only few results can be found in the literature about flame stretch effect in SI engine configurations.For this study, three different fuels (Methane, Propane, Iso-octane) were studied, but at different air-fuel lean mixture conditions, to present almost equivalent laminar flame speeds and thermo-dynamical properties at ignition timing condition. Besides those mixtures present different Lewis numbers which are relevant parameters to describe flame-stretch interactions. Mie-scattering tomography was then performed in an optical Spark Ignition (S.I.) engine. Using a high speed camera, flame propagation images were acquired through the piston. Thermodynamic analyses based on in-cylinder pressure traces were performed to estimate in-cylinder temperature and burnt mass fraction during the engine cycle.From the determination of flame areas, the global flame stretch and an equivalent propagation speed have been then defined and estimated. Results prove that mixtures have the same ranking in terms of flame stretch sensitivities as in the laminar regime. Probability density functions…
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Numerical and Experimental Investigation of Combustion Regimes in a Dual Fuel Engine

IFP Energies Nouvelles-Stephane Jay, Julian Kashdan, Cyprien Ternel
Universite d'Orleans-Christine Mounaïm-Rousselle
Published 2013-09-08 by SAE International in United States
Among the new combustion concepts envisaged to meet future regulations, the Dual Fuel (DF) concept is considered to be an attractive strategy due to its potential to reduce CO2 emissions and engine-out pollutant emissions levels. A small quantity of high-cetane fuel (Diesel) is injected in the combustion chamber in order to ignite a homogeneous mixture of air and a highly volatile fuel (gasoline in our study). The DF concept has been shown to achieve improved engine thermal efficiency and low engine-out NOx and soot emissions. However, the physical mechanisms controlling DF combustion and in particular, determination of the predominant combustion regime(s) are not yet well understood. In this study, numerical simulations (CFD) and optical engine measurements are used to investigate Dual Fuel combustion. The ECFM3Z combustion model (implemented in the IFP-C3D code) is presented in this paper in addition to preliminary results which have been performed for DF internal combustion (IC) engine simulations. The approach employed in this study allowed determination of the relative contributions of auto-ignition (AI), flame propagation (ECFM) and Burned Gas (BG)…
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Engine Performances and Emissions of Second-Generation Biofuels in Spark Ignition Engines: The Case of Methyl and Ethyl Valerates

CNRS-Guillaume Dayma, Philippe Dagaut
Universite D'Orleans-Christine Mounaïm-Rousselle
Published 2013-09-08 by SAE International in United States
As an alternative to second generation ethanol, valeric esters can be produced from lignocellulose through levulinic acid. While some data on these fuels are available, only few experiments have been performed to analyze their combustion characteristics under engine conditions. Using a traditional spark ignition engine converted to mono-cylinder operation, we have investigated the engine performances and emissions of methyl and ethyl valerates. This paper compares the experimental results for pure valeric esters and for blends of 20% of esters in PRF95, with PRF95 as the reference fuel. The esters propagate faster than PRF95 which requires a slight change of ignition timing to optimise the work output. However, both the performances and the emissions are not significantly changed compared to the reference. Accordingly, methyl and ethyl valerate represent very good alternatives as biofuels for SI engines. Future studies will focus on testing these esters in real application engines and performing endurance tests.
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Towards HCCI Control by Ozone Seeding

CNRS-Guillaume Dayma, Philippe Dagaut
Universite d'Orleans-Fabrice Foucher, Christine Mounaïm-Rousselle
Published 2013-09-08 by SAE International in United States
Nowadays, the main objectives in the automobile engine field are to reduce fuel consumption and pollutant emissions. HCCI engines can be a good solution to meet pollutant emission requirements and to achieve high combustion efficiency. However, before an HCCI engine is used as a conventional engine, several problems must be overcome, in particular control of the progression of combustion.Many studies have been conducted into possible control methods. A new strategy consists in using oxidizing chemical species such as ozone to seed the intake of a HCCI engine. As increasingly smaller ozonizers are now being designed, this kind of device could be integrated on a vehicle and on a HCCI engine, in order to control combustion phasing and promote the future use of this engine as a conventional engine.In the present study, experiments on a HCCI engine fuelled with iso-octane were carried out with ozone seeding in the intake. Results showed that when assisted by the addition of ozone, combustion can be enhanced and moved forward. Consequently, the use of oxidizing chemical species can be a…
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Impact of Fuel Properties and Flame Stretch on the Turbulent Flame Speed in Spark-Ignition Engines

Total Marketing and Service-Thomas Dubois
Universite d'Orleans-Pierre Brequigny, Christine Mounaïm-Rousselle, Fabien Halter, Bruno Moreau
Published 2013-09-08 by SAE International in United States
The current decrease in fossil energy resources requires a diversification of the liquid and gaseous fuels potentially consumable in internal combustion engines. The use of these fuels modifies the combustion process and the heat released as well. In a Spark Ignition (SI) engine, the heat released is mainly piloted not only by the mixture reactivity but also by its sensitivity to stretch effects. Only a few results can be found in the literature about stretch effects for SI engine configurations. The purpose of the present paper is to evaluate stretch effects on the flame front propagation in an optical SI engine and to investigate the relative importance of these effects depending on the fuel considered.Different air-fuel mixtures presenting different flame stretch sensitivities were selected. Four different engine regimes (1400, 1600, 1800 and 2000 rpm) were studied for all the mixtures in order to evaluate the impact of different turbulence intensities. In-cylinder pressure analyses were performed to determine the heat release rate and the crank angle corresponding to 5% of mass burned. At the same time,…
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Effects of Controlling Oxygen Concentration on the Performance, Emission and Combustion Characteristics in a Downsized SI Engine

IFP Energies Novelles-Stephane Richard
Universite d'Orléans-Jianxi Zhou, Christine Mounaïm-Rousselle, Fabrice Foucher
Published 2013-09-08 by SAE International in United States
In the present study, experiments were carried out in a single-cylinder downsized SI engine with different rates of oxygen (15% to 27% by volume in the total mixture of intake gases except fuel) and equivalence ratios (from 0.45 to 1). Therefore, the oxygen volume fraction is due to oxygen enrichment or nitrogen dilution. The study of the impact of controlling oxygen concentration on the combustion characteristics and emissions was performed at 1400 rpm, at several loads (Indicated Mean Effective Pressure (IMEP) from 400 to 1000 kPa). For each operation point, the spark advance and the intake pressure were adjusted simultaneously in order to maintain the load and obtain a minimum value of indicated Specific Fuel Consumption (SFC).The effect of oxygen concentration on the engine combustion characteristics was simulated by using the commercial software AMESim, with the combustion model developed by IFP-EN, and an adapted algorithm was used to avoid residual gas calibration. The in-cylinder pressures are calibrated with experimental data by adapted the integral length scale and tumble number values. By implementing a correlation for…
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Laser-Induced Incandescence to Study the Soot Particles Formation

PSA Peugeot-Citroën/DRIA-Olivier Pajot
Polytechnic Institute of Orléans-Andrei Boiarciuc, Fabrice Foucher, Bruno Moreau, Christine Mounaïm-Rousselle, Julien Sotton
  • Technical Paper
  • 2004-34-0093
Published 2004-10-20 by Transilvania University of Brasov in Romania
The Laser-Induced Incandescence is a technique allowing to study the soot formation in flames as well as inside the combustion chambers of the diesel engines. The technique is based on the blackbody radiation of the soot when irradiated with a laser beam or a laser sheet of sufficient high energy, the soot temperature being brought up to the particles vaporization temperature. The emitted signal is proportional to the soot volume fraction within the measurement volume while its temporal decay is the image of the soot particle cooling and it gives information regarding the soot mean diameter in the measurement volume if one fits an appropriate modeled curve on the experimental one.An analysis of soot formation in an isooctane/air diffusion flame was performed, the purpose being to determine the soot volume fractions and the particles mean diameter. Pairs of temporal LII signals detected at the two wavelengths of interest have been recorded for several locations of the measurement volume in the flame. Assuming that the particles are heated at the same temperature by the laser sheet,…