Optical diagnostics of early flame development in a DISI (direct injection spark ignition) engine fueled with n-butanol and gasoline

Merola, Simona Silvia; Tornatore, Cinzia; Irimescu, Adrian; Marchitto, Luca; Valentino, Gerardo

doi:10.1016/j.energy.2015.10.140

Cited by 30 publications

(11 citation statements)

References 44 publications

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“…In agreement with the literature [49,50], the change in the pressure near the spark plug determined a change in the linear tendency. As observed in previous works [25,39,40], flame kernel emission could be well distinguished at around 10 CADs after spark timing due to the luminosity of plasma induced between the spark plug's electrodes. After this time, the flame front propagated from the center of the combustion towards the cylinder walls.…”

Section: Resultssupporting

confidence: 57%

“…After this time, as shown in Figure 10, strong luminous flames were observed first systematically in the intake valves region and then in random locations near the walls. As observed in previous works [13,39,51,60], these flames were due to the diffusive combustion of stratified fuel in the injector region and on the piston surfaces. In terms of spectroscopic evidence (Figure 18b), these flames featured a continuous signal that increased with a wavelength similar to the blackbody curve described by Planck's radiation law [61].…”

Section: Hcoh + Hν → H + Hco Hcoh + Hν → H + Hcosupporting

confidence: 51%

“…Nonetheless, this mechanism can be considered to have a relatively reduced influence on overall efficiency; to put things into perspective, a concentration of 100 ppm of n-hexane in burned gas (the basis for HC as n-hexane equivalent measurements performed in this study) is equivalent to around 0.5% of the fuel content of stoichiometric air-fuel mixtures. The evolution of nitrogen oxides can be related to the thermal effect [20,39,40] with the highest value for the stoichiometric combustion process. With lean mixtures, the two competing effects (i.e., higher concentration of oxygen and lower burned gas temperature) featured different weights, with temperature having the more prominent influence.…”

Section: Resultsmentioning

confidence: 99%

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Flame Front Propagation in an Optical GDI Engine under Stoichiometric and Lean Burn Conditions

et al. 2017

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Lean fueling of spark ignited (SI) engines is a valid method for increasing efficiency and reducing nitric oxide (NO x ) emissions. Gasoline direct injection (GDI) allows better fuel economy with respect to the port-fuel injection configuration, through greater flexibility to load changes, reduced tendency to abnormal combustion, and reduction of pumping and heat losses. During homogenous charge operation with lean mixtures, flame development is prolonged and incomplete combustion can even occur, causing a decrease in stability and engine efficiency. On the other hand, charge stratification results in fuel impingement on the combustion chamber walls and high particle emissions. Therefore, lean operation requires a fundamentally new understanding of in-cylinder processes for developing the next generation of direct-injection (DI) SI engines. In this paper, combustion was investigated in an optically accessible DISI single cylinder research engine fueled with gasoline. Stoichiometric and lean operations were studied in detail through a combined thermodynamic and optical approach. The engine was operated at a fixed rotational speed (1000 rpm), with a wide open throttle, and at the start of the injection during the intake stroke. The excess air ratio was raised from 1 to values close to the flammability limit, and spark timing was adopted according to the maximum brake torque setting for each case. Cycle resolved digital imaging and spectroscopy were applied; the optical data were correlated to in-cylinder pressure traces and exhaust gas emission measurements. Flame front propagation speed, flame morphology parameters, and centroid motion were evaluated through image processing. Chemical kinetics were characterized based on spectroscopy data. Lean burn operation demonstrated increased flame distortion and center movement from the location of the spark plug compared to the stoichiometric case; engine stability decreased as the lean flammability limit was approached.

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Section: Resultssupporting

confidence: 57%

Section: Hcoh + Hν → H + Hco Hcoh + Hν → H + Hcosupporting

confidence: 51%

Section: Resultsmentioning

confidence: 99%

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Flame Front Propagation in an Optical GDI Engine under Stoichiometric and Lean Burn Conditions

et al. 2017

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“…However, the exhaust gas temperature is not a direct measurement of the in-cylinder temperature, and no accurate prediction can be made based on an insignificant difference in exhaust gas temperature. Thus, it is thought that butanol's lower adiabatic flame temperature of B33 could reduce the local combustion temperatures compared to gasoline, being the reason for slightly NOx reduction [36,42] at 35Nm. In addition, the marginally lower heat release rate at the end of the combustion phase could potentially reduce the NOx emissions with respect to gasoline.…”

Section: Gaseous Emissionsmentioning

confidence: 99%

Butanol-gasoline blend and exhaust gas recirculation, impact on GDI engine emissions

Hergueta

Bogarra

Tsolakis

et al. 2017

Fuel

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Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.

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“…An automatic interclass variance threshold method was applied starting from the light intensity histogram in order to obtain binary images. More details are provided by the same authors in a previous work [15].…”

Section: Introductionmentioning

confidence: 99%

Turbulent Flame Geometry Measurements in a Mass-Production Gasoline Direct Injection Engine

Villani

Aquino

2020

Energies

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Direct optical access to the combustion chamber of a gasoline direct injection (GDI) engine provides extremely valuable information about the combustion process. Experimental measurements of the geometric characteristics of the turbulent flame—such as the flame radius, flame center, flame edges and flame brush thickness—are of fundamental interest in support of the development and validation of any combustion model. To determine the macroscopic properties of sprays and flames, visualization and digital image processing techniques are typically used in controlled experimental setups like single-cylinder optical engines or closed vessels, while optical measurements on mass-production engines are more uncommon. In this paper the optical experimental setup (consisting of a high-speed camera, a laser light source and a data acquisition system) used to characterize the planar turbulent flame propagation in the cylinder of a 3.5 L GDI V6 mass-production engine, is described. The image acquisition process and the image processing that is necessary to evaluate the geometric characteristics of the propagating flame front, which are usually omitted in the referenced literature, are reported in detail to provide a useful guideline to other researchers. The results show that the step-by-step algorithm and the calculation formulae proposed allow to retrieve clear visualizations of the propagating flame front and measurements of its geometrical properties.

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Optical diagnostics of early flame development in a DISI (direct injection spark ignition) engine fueled with n-butanol and gasoline

Cited by 30 publications

References 44 publications

Flame Front Propagation in an Optical GDI Engine under Stoichiometric and Lean Burn Conditions

Flame Front Propagation in an Optical GDI Engine under Stoichiometric and Lean Burn Conditions

Butanol-gasoline blend and exhaust gas recirculation, impact on GDI engine emissions

Turbulent Flame Geometry Measurements in a Mass-Production Gasoline Direct Injection Engine

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