Open AccessTowards better correlation between optical and commercial spark ignition engines through quasi-dimensional modeling of cycle-to-cycle variability
Author(s) -
Adrian Irimescu,
Simona Silvia Merola,
Bianca Maria Vaglieco
Publication year - 2022
Publication title -
thermal science/thermal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.339
H-Index - 43
eISSN - 2334-7163
pISSN - 0354-9836
DOI - 10.2298/tsci200511333i
Subject(s) - spark (programming language) , combustion , context (archaeology) , automotive engineering , environmental science , ignition system , mean effective pressure , spark ignition engine , propulsion , thermodynamic cycle , computer science , internal combustion engine , aerospace engineering , mechanical engineering , engineering , compression ratio , chemistry , paleontology , organic chemistry , biology , programming language
Internal combustion engines are still the main choice when considering propulsion technology in the transport sector. Spark ignition (SI) units offer the advantage of good efficiency with simpler after-treatment systems. Lean operation is a promising strategy that would further improve efficiency, but requires mitigation of cycle-to-cycle variability (CCV). Within this context, and given the increasing trend of using simulation based evaluations during engine development, the current work investigated combustion in an optical SI engine through measurements and quasi-dimensional simulation. The possibility of visualizing in-cylinder processes provides unique insight, but also introduces complications with respect to commercial engines. For this reason, quasi-dimensional simulation was applied so as to better understand the factors that induce CCV. For the specific case of the investigated engine, cycle-to-cycle measured exhaust air-fuel ratio was found to be directly correlated to variations of engine output. Several routes of incorporating these effects into simulations were evaluated. Introducing a random component in the period of laminar-turbulent flame transition was found to ensure good grounds for simulating peak pressure variability. Indicated mean effective pressure (IMEP) on the other hand was found to depend less on the initial stages of combustion and was strongly correlated to aforementioned variability of exhaust air-fuel ratio.