Lean Burn Flame Kernel Characterization for Different Spark Plug Designs and Orientations in an Optical GDI Engine

Giovanni Cecere, Adrian Irimescu, Simona Silvia Merola, Luciano Rolando and Federico Millo
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Giovanni Cecere: CNR STEMS_Science and Technology Institute for Sustainable Energy and Mobility, Via Guglielmo Marconi 4, 80125 Napoli, Italy
Adrian Irimescu: CNR STEMS_Science and Technology Institute for Sustainable Energy and Mobility, Via Guglielmo Marconi 4, 80125 Napoli, Italy
Simona Silvia Merola: CNR STEMS_Science and Technology Institute for Sustainable Energy and Mobility, Via Guglielmo Marconi 4, 80125 Napoli, Italy
Luciano Rolando: Energy Department, Politecnico di Torino, 10129 Torino, Italy
Federico Millo: Energy Department, Politecnico di Torino, 10129 Torino, Italy

Energies, 2022, vol. 15, issue 9, 1-17

Abstract: Lean burn spark ignition (SI) engines represent an effective solution for improving fuel economy and reducing exhaust emissions and can be implemented both in conventional and hybrid powertrains. On the other hand, lean operation increases cyclic variability with negative impact on power output, engine efficiency, roughness, and operating stability. Although this phenomenon has been widely investigated, the effects of flow field on the inception and development of flames in direct injection spark ignition (DISI) engines under lean burn conditions is not yet completely understood. In particular, the effect of spark plug geometry and electrode orientation with respect to tumble motion has been minimally investigated. For these reasons, two different spark-plug geometries (i.e., single- and double-ground electrode) and three different orientations (i.e., cross-, counter-, and uni-flow with respect to the direction of tumble motion) were investigated in an optically accessible DISI engine for understanding their influence on the initial phase of combustion. The relative air–fuel ratio (AFR rel ) was changed from stoichiometric to lean burn (1.00 to 1.30) for different spark timings around the maximum brake torque setting at fixed engine speed (2000 rpm). An image processing procedure was developed for evaluating the morphological parameters of flame kernels and studying the effects of spark plug design on engine operating stability. With a focus on the correlation between the position where ignition occurs with the subsequent locations of the flame kernel during the first phases of the combustion process, the analysis allowed the gathering of a better understanding of the influence that the electrodes’ geometries and orientation can have on the first stages of combustion development.

Keywords: spark plug design; flame kernel; optically accessible engine; lean burn (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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