Investigation on the Influence of Nozzle Shape on Supersonic Hydrogen Jet

The global energy crisis and environmental pollution problems have accelerated the process of the new energy technology revolution. Hydrogen energy is considered as one of the main forces of future green energy. Hydrogen internal combustion engines (H2ICES), as one of the main power forms of hydrogen energy application, have received extensive attention. It is worth noting that the characteristics of hydrogen jet affect the combustion performance and emission performance of hydrogen engines because they are directly related to the mixture formation process. In this paper, for a certain inner-opening direct injection (DI) nozzle, the Computational Fluid Dynamics (CFD) research method is used to explore the jet characteristics of the straight-hole (SH) nozzle, the diverging-tapered-hole (DTH) nozzle, and the stepped-hole (STH) nozzle from aspects such as mass flow rate, hydrogen mass fraction field, velocity field, and pressure field. The results show that for inward-opening DI nozzles with a cap, the nozzle inlet size within the shielding cap is the dominant factor influencing hydrogen flow, as it primarily determines the jet characteristics. Conversely, nozzle volume and outlet size have minimal impact on the mass flow rate. Under identical inlet conditions, the DTH nozzle exhibits superior flow performance. These results will have certain guiding significance for the design of DI nozzles and promote the commercial application process of H2ICES.