To achieve global climate goals, greenhouse gas emissions must be drastically reduced. The energy and transportation sectors are responsible for about one third of the greenhouse gases emitted worldwide, and they often use internal combustion engines (ICE). One effective way to decarbonize ICEs may be to replace carbon-containing fossil fuels such as natural gas entirely, or at least partially, with hydrogen. Cost-effective development of sustainable combustion concepts for hydrogen and natural gas/hydrogen mixtures in ICEs requires the intensive use of fast and robust simulation tools for prediction. The key challenge is appropriate modeling of flame front propagation.
This paper evaluates and applies different approaches to modeling laminar flame speeds from the literature. Both appropriate models and reaction kinetic calculations are considered. The most promising approaches are then combined with various approaches for turbulent combustion as the basis for determining zero-dimensional burn rates. In developing these approaches, one particular challenge is to make the models able to correctly represent flame front propagation with a 0-100% share of hydrogen in the mixture as well as consider the resulting effects. In particular, the destabilizing effects of an increasing share of hydrogen, which can be described by the Lewis number not equal to one, are examined.
Finally, validation of the model results involved not only classic comparison of analyzed cylinder pressure curves and other engine performance parameters but also direct comparison of measured and modeled flame front propagation based on experimental measurement data from ion current probes. The measurements were made on a single-cylinder research engine with a cylinder head equipped with ion current probes attached to the spark plug sleeve around the spark plug.