Enhancing Dual Fuel Combustion Simulation: A Novel Geometric Approach for Accurate Flame Entrainment Estimation

Maritime transportation plays a vital role in the economy and is one of the most energy-efficient modes of transportation. However, it is a growing source of greenhouse gas emissions. A potential solution to lower carbon emissions from maritime transport is to use renewable fuels in marine engines. Hydrogen or methanol can serve as the primary energy source in internal combustion (IC) engines. However, their high autoignition temperatures require an external ignition source to start combustion in compression ignition (CI) engines. The Dual Fuel (DF) approach offers an effective method for incorporating these fuels. To accurately simulate dual fuel combustion, certain parameters need to be carefully addressed. One crucial parameter to investigate is estimating the flame entrainment area, as it directly affects the mass burning rate. In this work, a novel geometric approach is developed to estimate the evolution of the flame entrainment area. This model is integrated into a multi-zone dual fuel combustion model in GT-Power and evaluated against experimental data from a single-cylinder engine (SCE) running on methanol in dual fuel mode, specifically 25 different cases with a bore size of 240 mm (SCE1) and 25 cases with a bore size of 256 mm (SCE2). The results show that using the new flame area model reduces the root mean square error (RMSE) in predicting combustion phasing (CA90) from about 10 crank angle degrees (CAD) to approximately 3.5 CAD for SCE1 and from 18 CAD to 8 CAD for SCE2. Additionally, there is a reduction in RMSE for predicting the indicated mean effective pressure (IMEP), from 2.3 bar to 1.3 bar for SCE1 and from 1.5 bar to 1.0 bar for SCE2. Significant improvements are also observed in the heat release rate curve, specifically in the tail of combustion.