Comparative Analysis between a Barrier Discharge Igniter and a Streamer-Type Radio-Frequency Corona Igniter in an Optically Accessible Engine in Lean Operating Conditions

Cruccolini, Valentino; Discepoli, Gabriele; Ricci, Federico; Petrucci, Luca; Grimaldi, Carlo N.; Papi, Stefano; Re, Massimo Dal

doi:10.4271/2020-01-0276

Cited by 26 publications

(46 citation statements)

References 53 publications

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“…The total injected mass was weighted through a Micron AD scale (±10 mg accuracy) after 20,000 consecutive injection events at the same gasoline pressure and injector ET; the mass per cycle (i.e., the dynamic flow rate Q according to SAE J1832 [42]) was then computed. Further details about the measurement apparatus can be found in Table 2 and in previous works of our research group [11,15,32,33]. Table 2.…”

Section: Optical Enginementioning

confidence: 99%

“…A Vision Research Phantom V710 high-speed CMOS camera coupled with a Nikon 55-mm f/2.8 lens was used to record the natural luminosity [43] of streamers and early flames. The framerate was increased to 79 kHz (i.e., 79,000 fps), unlike previous works [11,15,32,33], because the focus was on the streamer motion and on the characterization of the first instants in which combustion takes place. Therefore, the frame was magnified around the igniter main electrode, without detecting the entire quartz crown area (frame size resulted to be 32.1 × 32.1 mm).…”

Section: Imaging Systemmentioning

confidence: 99%

“…Shawal et al [31] proposed a semiautomatic method in which the initial binarization is implemented using the threshold of the previous image; the new threshold is calculated again as a linear function of the average intensity in this pre-estimated burned area. Unlike Otsu's method, this was found to be effective for a large span of in-cylinder conditions, from stoichiometric to lean mixtures, and from the dark first frames of combustion onset to the brightest ones [11,15,32,33].…”

Section: Introductionmentioning

confidence: 99%

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An Optical Method to Characterize Streamer Variability and Streamer-to-Flame Transition for Radio-Frequency Corona Discharges

et al. 2020

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In recent years, radio-frequency corona ignition gained increasing interest from the engine research community because of its capability to extend the engine stable operating range in terms of lean and EGR dilution. The corona discharge generates streamers coming from a star-shaped electrode, generally consisting of four or five tips. The temporal and spatial variability of such streamers in length, orientation, and branching can be factors that affect the combustion onset and, therefore, engine cycle-to-cycle variability. Generally, the latter is reduced with respect to a conventional spark igniter at the same air–fuel ratio, but still present. In this work, analysis on the corona discharge and on the subsequent combustion onset was carried out in an optically accessible engine by means of the detection, via high-speed camera, of the natural luminosity of streamers and flames. A method to characterize spatial and temporal variability in motored conditions is firstly presented. A statistical analysis of the streamer behavior was performed, by separately analyzing the streamers generated by each tip of the star-shaped electrode. Finally, an original method aimed at determining the moment of the first flame appearance, caused by the combustion onset, is presented. The outcome of this work can be used to improve the knowledge on corona discharge, in particular on the stochastic behavior that characterizes the streamers. The presented optical analysis can also be adapted to other volumetric, single- or multi-point ignition systems.

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Section: Optical Enginementioning

confidence: 99%

Section: Imaging Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Optical Method to Characterize Streamer Variability and Streamer-to-Flame Transition for Radio-Frequency Corona Discharges

et al. 2020

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“…The upper limit is the breakdown voltage (BDV [24]), which implies a transition from non-equilibrium plasma streamers to thermal near-equilibrium plasma, typical of spark igniters. This igniter was already tested by our research group in an optical engine [8,15,22,23,25] and in another calorimeter [18,19], different from the one used in this work since there was no optical access. Fig.…”

Section: Rf Corona Ignitermentioning

confidence: 99%

“…Regarding the latter, low-temperature or non-equilibrium plasma is able to enhance the combustion not only via thermal effect (the predominant in the spark discharge), but also via kinetic and transport effects [11]. Among several low-temperature plasma technologies, such as nanosecond-pulsed discharge [12], microwave discharge [13] and dielectric-barrier discharge [14], radio-frequency (RF) corona discharge is one of the most promising [15]. Several works showed its capability to improve lean or EGR-dilution tolerance [8,16].…”

Section: Introductionmentioning

confidence: 99%

Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter

et al. 2020

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In recent years, radio-frequency corona igniters have been extensively studied for their capability to ensure an effective ignition also in lean or diluted mixtures. Corona ignition is volumetric, with streamers coming from a star-shaped electrode. During the discharge, many radicals and excited species, able to speed up the combustion onset, are generated. At the same time, corona igniters are able to release a considerable amount of thermal energy inside the combustion chamber. The correct determination of such energy is crucial to evaluate the effectiveness of the ignition. In this work, corona discharge is experimentally evaluated inside an optical vessel. In this apparatus, the released thermal energy is measured by means of pressure-based calorimetry, and at the same time the natural luminosity of the streamers is recorded with a high-speed camera. The goal is to find a relationship between thermal energy release and streamers luminosity. Tests are performed using nitrogen as medium, at different pressure levels inside the vessel. The peak electrode voltage is varied to characterize the igniter behaviour in different operating conditions. The results of this work can be used to quantify the corona ignition capabilities to involve a wide amount of medium while releasing a high amount of thermal energy. A repeatability evaluation of streamer evolution is investigated as well.

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Modeling of thermal and kinetic processes in non-equilibrium plasma ignition applied to a lean combustion engine

Zembi

Cruccolini

Mariani

et al. 2021

Applied Thermal Engineering

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Comparative Analysis between a Barrier Discharge Igniter and a Streamer-Type Radio-Frequency Corona Igniter in an Optically Accessible Engine in Lean Operating Conditions

Cited by 26 publications

References 53 publications

An Optical Method to Characterize Streamer Variability and Streamer-to-Flame Transition for Radio-Frequency Corona Discharges

An Optical Method to Characterize Streamer Variability and Streamer-to-Flame Transition for Radio-Frequency Corona Discharges

Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter

Modeling of thermal and kinetic processes in non-equilibrium plasma ignition applied to a lean combustion engine

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