Numerical analysis of central fluid effects on GH2/GO2 coaxial injector

To study the effect of the central fluid on the combustion characteristics, a numerical study of a single-element injector with gaseous hydrogen and gaseous oxygen (GH2/GO2) propellants were performed at atmospheric pressure. The flow field characteristics of three cases: fuel-rich combustion with an oxygen centre, fuel-rich combustion with a hydrogen centre, and oxygen-rich combustion with a hydrogen centre were discussed. The combustion process is simulated using the constant Reynolds-averaged Navier-Stokes (RANS) technique. The results show that: Under fuel-rich conditions, the hydrogen-centered injector shows a 29.3% reduction in axial distance required for the central combustion zone to reach 800K, accompanied by a 11.9% decrease in injector plate temperature. Oxygen-centered injector under oxygen-rich conditions with the same mass flow rate and theoretical combustion temperature shows a 59.8% reduction in the 800K attainment distance, a 27.2% decrease in injector plate temperature. The H2 center enhances the degree of mixing and reduces the thermal load on the injector faceplate, but at the cost of an elevated thermal load on the chamber walls. Furthermore, this scheme contributes to improving both combustion efficiency and outlet gas uniformity.