Numerical Simulation of a Prechamber-Ignited Lean-Burn Gas Engine by Means of Predictive Combustion Models

Authors Abstract
In the recent period, lean-burn gas operation has been gaining large attention both in the marine sector and for power generation since it allows to achieve very low Nitrogen Oxides (NOx) emissions and to reduce carbon footprint compared to conventional diesel engines. However, to ensure a stable and efficient combustion process, innovative ignition systems able to deliver high energy content have to be considered. The employment of an active Pre-Combustion Chamber (PCC) ignition system is nowadays considered one of the most effective solutions for large-bore gas engines.
In active PCC engines, the lean gas mixture in the Main Chamber (MC) is ignited by hot jets flowing from the PCC, resulting from a near-stoichiometric gas spark-assisted combustion in the PCC. The ability to describe and model both the PCC and MC combustion process with (zero-dimensional/one-dimensional) 0D/1D models has gained great importance in the last years since it could enable the exploitation of predictive simulation tools as a support to testing activities in the engine development phase.
In this regard, in this activity a simulation methodology for a PCC gas engine is presented. Two combustion models, one for the PCC and the other for the MC phenomena, were investigated for the combustion process simulation. Experimental measurements from a six-cylinders Wärtsilä engine were used to assess the predictive capabilities of the numerical model, considering several engine operating conditions and engine calibrations. Moreover, three different PCC systems were investigated in this study to evaluate the model accuracy also considering different PCC shapes and geometry features. The investigated combustion models showed great accuracy in simulating the ignition process and combustion behavior of the analyzed engine.
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Accurso, F., Piano, A., Millo, F., Caputo, G. et al., "Numerical Simulation of a Prechamber-Ignited Lean-Burn Gas Engine by Means of Predictive Combustion Models," SAE Int. J. Engines 16(5):623-641, 2023,
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Dec 5, 2022
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Journal Article