3D-CFD Simulations of H2 ICEs: A Preliminary Evaluation of a Laminar Flame Speed Correction for Thermo-Diffusive Instability

In recent years, climate change and geopolitical instability have intensified the focus on sustainable power generation. This shift seeks alternatives that balance environmental impact, cost-effectiveness, and practicality. Specifically, in transportation and power generation, electric motors face challenges against internal combustion engines due to the high cost and mass of batteries required for energy storage. This makes electric solutions less favorable for these sectors. Conversely, internal combustion engines, when properly fueled, offer cost-effectiveness and a quasi-environmentally-neutral option. To address these challenges, researchers have explored e-fuels derived from renewable sources as a carbon-neutral supply for internal combustion engines. Among these, hydrogen is particularly promising. In hydrogen-powered internal combustion engines, 3D-CFD (Computational Fluid Dynamics) in-cylinder models are crucial. Once validated, these models can speed up the design process. A key challenge in simulating H2 combustion is accurately representing flame thermo-diffusive instabilities in lean mixtures, which are vital for peak engine efficiency. Accurate representation of the combustion process under lean conditions is thus mandatory in 3D-CFD models. This study represents a preliminary effort to incorporate thermo-diffusive instabilities into a 3D-CFD in-cylinder framework. An extensively validated numerical framework was modified to include instability-induced acceleration in flame propagation speed. The outcomes were analyzed and compared with results obtained without the correction term. Although improvements were limited to certain operating conditions, the study underscored the importance of considering the influence of turbulence on instability.