Similarity and normalization study of fuel spray and combustion under ultra-high injection pressure and micro-hole diameter conditions–spray characteristics

The compression-ignition engine has been widely applied in various fields due to its high efficiency, fuel economy, and adaptability. With the increasing awareness of environmental issues, emission regulations have become more stringent, leading to a growing demand for high-pressure and small-sized engines. Since developing new engines is often both costly and time-consuming, leveraging the similarity between spray and combustion processes for new engine development can significantly reduce the required resources and time. However, to date, systematic research on the similarity and normalization of sprays and combustion processes, especially under ultra-high injection pressure and micro-hole diameter conditions, remains lacking. In this study, conversion models and normalization models for spray characteristics were developed based on both time scale and multi-dimensional space scale. The spray transformation and normalization were verified for different aperture sizes, injection pressures, ambient temperatures, densities, and pressures. The results show that the models exhibit good interchangeability and normalization effects. This research outcome will provide valuable references for optimizing and designing more efficient and environmentally friendly internal combustion engines.