Abstract
Because of significantly different physical and chemical properties of hydrogen, compared to hydrocarbons, running an engine on hydrogen or modeling the combustion of hydrogen in engines is not straightforward. This paper focuses on modeling the power cycle of a hydrogen-fueled spark-ignition engine. The authors have investigated the laminar burning velocity u_1 of hydrogen/air mixtures, with allowance for residuals, as this is a fundamental parameter in turbulent burning velocity models. The correlation for u_1 was evaluated in a quasi-dimensional engine code by a comparison to experimental data on a single cylinder hydrogen engine. A two-equation combustion model was used to allow for flame brush thickness effects. Several models for the turbulent burning velocity were used to provide values for the turbulent 'entrainment' velocity. All models were able to correctly predict the effects of varying compression ratio and ignition timing. The ability to recover the effects of changes in equivalence ratio, one of the features in which a hydrogen engine differs clearly from hydrocarbon-fueled engines, is shown to be the benchmark to distinguish between models.
