抄録
It is reported that combustion of rich hydrogen mixture plume that is formed in the middle or just after the injection named PCC ( Plume Ignition Combustion Concept) is effective to reduce NOx formation drastically without offering any trade-offs on thermal efficiency in high output power operation in high pressure direct injection hydrogen engines. In this study fundamental requirements to achieve further reduction in NOx formation in PCC are investigated by optimizing ignition timing with the assist of visualization technology of flame propagation in the combustion chamber based on high speed laser shadowgraphy. As a result it was clarified that requirement of reducing NOx formation is controlling air entrained to hydrogen jet by shortening duration from injection of hydrogen to ignition. It was also made clear that additional approach to reduce unburned hydrogen is required in case entrained air is too low.
