Combustion Behavior of an RF Corona Ignition System with Different Control Strategies

Cimarello, Alessandro; Cruccolini, Valentino; Discepoli, Gabriele; Battistoni, Michele; Mariani, Francesco; Grimaldi, Carlo N.; Re, Massimo Dal

doi:10.4271/2018-01-1132

Cited by 19 publications

(34 citation statements)

References 36 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%

“…Nevertheless, none of the previous works and methods were specifically dedicated to corona streamer detection and analysis. As the typical discharge duration is tens (or few hundreds, at most) of microseconds [32], an original methodology, consisting of a high-speed image processing workflow, was developed in this work. The first method here presented is the evaluation of streamer repeatability.…”

Section: Introductionmentioning

confidence: 99%

“…Corona discharge is featured with a strong randomness, which can contribute to the overall CCV. Depending on discharge parameters (mainly the electrode voltage [21,32,34]), pressure and turbulence in the combustion chamber, and mixture composition, streaming behavior is different. Phenomena like branching, transition to arc, and lack of streamers might occur.…”

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%

Section: Introductionmentioning

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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Advanced Ignition System to Extend the Lean Limit Operation of Spark-Ignited (SI) Engines—A Review

Vedharaj

2021

Energy, Environment, and Sustainability

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Experimental characterisation of the thermal energy released by a Radio-Frequency Corona Igniter in nitrogen and air

et al. 2020

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The Radio-Frequency Corona Ignition System is characterised by a wide initial combustion volume and precursors production, via radical insemination by the streamers, in addition to high released thermal energy. These features lead to faster combustion, a higher tolerance for lean mixtures and EGR dilutions and, in general, more adaptability. The thermal energy released by the igniter to the surrounding medium can help to understand the performance, the behaviour and the application range. This paper proposes a systematic experimental analysis of the thermal energy released by the igniter at room temperature, via pressure-based calorimetry. This analysis, carried out at different pressures (up to 10 bar) and medium type (air or nitrogen), is extended to the whole range of the corona igniter control parameters, namely streamer duration and driving voltage. The latter is proportional to the maximum electrode voltage, as shown in the model here presented, and as confirmed by experiments. The results show, for all the vessel pressures, the high energetic efficiency of the ignition system and the high amount of the released energy. The latter is found to increase linearly with the corona streamers duration and quickly with the driving voltage up to the streamer-to-arc transition threshold. The efficiency tends to reach a defined upper limit. For each tested point, the energy released to pure nitrogen is higher than to air, which evidences the impact of the oxygen presence under streamer exposure.

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Combustion Behavior of an RF Corona Ignition System with Different Control Strategies

Cited by 19 publications

References 36 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

Advanced Ignition System to Extend the Lean Limit Operation of Spark-Ignited (SI) Engines—A Review

Experimental characterisation of the thermal energy released by a Radio-Frequency Corona Igniter in nitrogen and air

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