Numerical Investigation of flow and combustion process in a hydrogen direction injection rotary engine

The high power-to-weight ratio and zero carbon emission hydrogen rotary engine (HRE) is an attractive development direction of hydrogen-powered systems, which is of great significance in expanding the hydrogen energy diversified utilization and promoting greenhouse gas (GHG) emission reduction. In this paper, a direct injection HRE simulation model coupling chemical reaction kinetics is constructed. The flow and combustion processes are visually presented using computational fluid dynamics (CFD) means, and the effect of the air intake method and hydrogen injection timing on the mixture formation and combustion performance are analyzed. Research finds that the combustion pressure, peak pressure, indicated work and indicated power of the HRE are larger when using methods of the compound or side intake or delaying hydrogen injection strategy. Due to the forward flame propagation characteristics, the combustion process mainly occurs in the front part of the combustion chamber, and the mixture distribution in this area and aggregation near the ignition chamber are more favorable to improving the combustion performance. More gas fuel gathered in the leading or end regions of the chamber will affect the burn rate in the later combustion stage. The preferred scheme is compound AIM with HIT at the early compression stage (CAIM-190), and its peak pressure, indicated work and indicated power improve by 30.9%, 25.5% and 26.6% respectively while combustion duration shortens by 15.3% when comparing to the scheme of minimum peak pressure (PAIM-286). This study can offers basic data to promote the HRE achieving efficient combustion and zero carbon emissions.