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Effect of Spark Discharge Duration and Timing on the Combustion Initiation in a Lean Burn SI Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 06, 2021 by SAE International in United States
Event: SAE WCX Digital Summit
Meeting the increasingly stringent emission and fuel efficiency standards is the primary objective of the automotive research. Lean/diluted combustion is a promising avenue to realize high-efficiency combustion and reduce emissions in SI engines. Under the diluted conditions, the flame propagation speed is reduced because of the reduced charge reactivity. Enhancing the in-cylinder charge motion and turbulence, and thereby increasing the flame speed, is a possible way to harness the combustion process in SI engines. However, the charge motion can have a significant effect on the spark ignition process because of the reduced discharge duration and frequent restrikes. A longer discharge duration can aid in the formation of the self-sustained flame kernel and subsequent stable ignition. Therefore, an empirical study is undertaken to investigate the effect of the discharge duration and ignition timing on the ignition and early combustion in a port fueled SI engine, operated under lean conditions. The discharge duration is modulated from 1 ms to 8 ms through a continuous discharge strategy. The discharge current and voltage measurements are recorded during the engine operation to characterize the discharge process. The in-cylinder charge is diluted using fresh air to achieve lean combustion. The in-cylinder pressure measurement and heat release analysis are used to investigate the ignition and combustion characteristics of the engine. Preliminary results indicate that while the discharge duration has a marginal effect on the ignition delay, cyclic variations are notably impacted.