The influence of hydrogen injection position on the combustion process of a hydrogen direct injection X-type rotary engine with biased combustion chamber.

In the context of global efforts to achieve carbon neutrality, the internal combustion engine industry is progressively shifting toward cleaner fuels. This study examines the impact of direct hydrogen injection position on the combustion process of an X-rotor engine equipped with an offset combustion chamber, aiming to enhance rotor performance and mitigate pollutant emissions. Utilizing CONVERGE software, a three-dimensional dynamic computational fluid dynamics (CFD) model was constructed. The findings indicate that hydrogen injected directly into the cylinder interacts with the mainstream flow during the mixture formation process. Hydrogen entrainment occurs due to the influence of the mainstream flow, leading to the formation of vortices in the injection region. Generally, hydrogen injected from position III is more likely to blend with the gasoline-air mixture in the cylinder, resulting in a homogeneous combustible mixture that promotes effective flame propagation. Specifically, the highest in-cylinder pressure (14.1% and 19.2% greater than injection positions I and II, respectively) is achieved at this injection position. Additionally, the combustion propagation speed is the fastest, and cumulative heat release reaches its peak at 18.07 J, with an indicative thermal efficiency of 25.8%. While these conditions reflect optimal combustion performance, they also correspond to the highest levels of nitrogen oxides (NO x) and carbon monoxide (CO) emissions. • Designed a hydrogen direct injection X-type rotary engine with biased combustion chamber. • A three-dimensional model of X-type rotary engine was developed. • The hydrogen from injection position III is favorable for mixture formation and combustion. • The highest pressure in the cylinder was obtained at the injection position III. [ABSTRACT FROM AUTHOR]