Abstract
The mixing of hydrogen into natural-gas fuel in an SI engine extends the lean limit and promotes the combustion, but at the same time easily causes a hard knock. In this study. pressure histories and thermal efficiencies were measured with a single-cylinder test engine for various engine parameters such as equivalence ratio, ratio of hydrogen to natural-gas fuel, ignition timing, and compression ratio. Based on the experimental results, the knock characteristics were discussed with special attention to the extremely high burning velocity.
