A Quasi-Dimensional Burn Rate Model for Pre-Chamber-Initiated Jet Ignition Combustion

Autor: Francesco Salerno, Michael Bargende, André Kulzer, Michael Grill, Patrick Burkardt, Marco Günther, Stefan Pischinger, Jonas Villforth
Rok vydání: 2023
Zdroj: SAE Technical Paper Series.
ISSN: 2688-3627
0148-7191
DOI: 10.4271/2023-01-0184
Popis: Prospective combustion engine applications require the highest possible energy conversion efficiencies for environmental and economic sustainability. For conventional Spark-Ignition (SI) engines, the quasi-hemispherical flame propagation combustion method can only be significantly optimized in combination with high excess air dilution or increased combustion speed. However, with increasing excess air dilution, this is difficult due to decreasing flame speeds and flammability limits. Pre-Chamber (PC) initiated jet ignition combustion systems significantly shift the flammability and flame stability limits towards higher dilution areas due to high levels of introduced turbulence and a significantly increased flame area in early combustion stages, leading to considerably increased combustion speeds and high efficiencies. By now, vehicle implementations of PC-initiated combustion systems remain niche applications, especially in combination with lean mixtures. This is also due to challenges regarding cold-start, combustion stability at low loads, and emissions. Nevertheless, PC ignition systems allow overall engine efficiencies >45%. Therefore, a market launch of an engine using globally lean mixtures ignited by a PC system is desirable. This requires a fast-running and predictive physical model to conduct robust design studies and complement existing testing methodologies (3D-CFD, experimental). This paper addresses the development of a quasi-dimensional burn rate model for PC ignition combustion systems. The presented modeling approach combines the well-established two-zone entrainment model (main-chamber) with a semi-empirical PC model that aims to detect the PC influence on the main-chamber combustion. Dedicated models predict the impact of the jet-induced turbulence and the increased flame area. The models are integrated into the so-called cylinder module developed at IFS (Institute of Automotive Engineering Stuttgart). For the model validation, measurement data of a single-cylinder research engine using different fuels (E1001, RON95E102), loads (IMEP = 6 − 15 bar), excess air dilutions (λ = 1 − 2) and compression ratios (16.41, 12.62) are used, showing a satisfactory prediction of the burn rate and pressure curve.
Databáze: OpenAIRE
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