Analysis of RF Corona Ignition in Lean Operating Conditions Using an Optical Access Engine

Cimarello, Alessandro; Grimaldi, Carlo N.; Mariani, Francesco; Battistoni, Michele; Re, Massimo Dal

doi:10.4271/2017-01-0673

Cited by 29 publications

(41 citation statements)

References 31 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%

“…LTP igniters were found to be capable of ensuring a higher lean/diluted combustion robustness. At the same time, electrode erosion or fouling-typical of spark igniters-was found to be minimized [6,12,[14][15][16]. These advantages are related to the three combustion enhancement pathways: thermal, kinetic, and transport [17].…”

Section: Introductionmentioning

confidence: 99%

“…These advantages are related to the three combustion enhancement pathways: thermal, kinetic, and transport [17]. Among all the LTP systems, RF corona was intensively studied in recent years [18][19][20][21], especially in optical engines [11,14,22], to characterize its ability to speed up the early flame kernel generation [15].…”

Section: Introductionmentioning

confidence: 99%

“…Independently of the engine application, optical techniques are increasingly used and improved to understand in-cylinder phenomena: trapped mass at intake valve closing [23], Sauter mean diameter for gasoline direct injection (GDI) [24], interaction between turbulent field and flames [25], and flame front characteristics (e.g., maximum propagation speed, circularity factor) [26]. In most of the cases, a very good match between optical and thermodynamic data was found, especially in terms of mass fraction burned and/or volume fraction burned [15,27]. Optical techniques are also used in simplified configurations, such as constant-volume chambers, e.g., to determine the amount of energy released in air by a spark discharge [28].…”

Section: Introductionmentioning

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: Introductionmentioning

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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A high efficiency lean-burn mono‑fuel heavy‑duty natural‑gas engine for achieving Euro VI emissions legislation and beyond – part 2

Barroso¹,

Auld²,

Manuelyan³

et al. 2019

Proceedings

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Fundamentals, Evolution, and Modeling of Ignition Systems for Spark Ignition Engines

Kumar

Ágarwal

2021

Energy, Environment, and Sustainability

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The advancement of technologies has led researchers to explore new ways to comply with stringent emission norms globally and fulfil the energy requirements. The trends in engine development favour computational studies for initial investigations due to lesser time demand and economy. In a spark ignition (SI) engine, ignition of the fuel-air mixture is achieved by the spark discharge across the spark plug electrodes. The discharge is of very high intensity for a very short interval, providing sufficient energy in the form of plasma kernel to initiate chemical reactions necessary to generate a self-sustaining flame. Direct injection SI combustion system is considered an upcoming next-generation technology capable of meeting stringent emission norms with improved engine performance. Conventional spark plug system undergoes various issues such as erosion of spark plug, heat losses at the electrodes, hindrance in working at high in-cylinder pressures, and fixed spark location. Therefore, the researchers explore alternate ignition concepts/ systems that provide greater flexibility than conventional ignition systems. These alternate ignition concepts/ systems include laser ignition, turbulent jet ignition, corona ignition, and microwave ignition. These all are also referred to as advanced ignition systems. Advanced ignition has emerged as an alternative way to ignite leaner fuel-air mixture owing to higher engine performance and lower emissions. These systems offer significant advantages; however, they are still under research, and many challenges need to be overcome before they are commercialized. In this chapter, the evolution of the spark ignition systems has been discussed. Modelling aspects of spark ignition engines using 1D and 3D simulation tools have been summarised. The working of these advanced ignition systems has been discussed in detail, and their challenges are also summarised.

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Analysis of RF Corona Ignition in Lean Operating Conditions Using an Optical Access Engine

Cited by 29 publications

References 31 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

A high efficiency lean-burn mono‑fuel heavy‑duty natural‑gas engine for achieving Euro VI emissions legislation and beyond – part 2

Fundamentals, Evolution, and Modeling of Ignition Systems for Spark Ignition Engines

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