Fuel Effects on the Combustion Flow Structure behind a Splitter Plate of a Rocket Injector

Abstract

A computational study is performed to investigate the impact of fuel sensitivity on a high-pressure combustion flow fields of a rocket-type injector through a comparison between two fuels, hydrogen and methane. A two-dimensional model with a splitter plate, which represents a rocket engine injector, is adapted. The investigation focuses on the near-field flow and combustion dynamics of both GOX/GH₂ and GOX/GCH₄ injectors. The compressible Navier–Stokes equations are solved with detailed chemical kinetic mechanisms in a manner of direct numerical simulation. The result demonstrates that the near-field flow and combustion structures of the injector are affected by changing the momentum flux ratio of injector condition. Non-uniform temperature distributions, established behind the injector post, are mainly determined with the amount of inflowing high-temperature combustion and unburned fuel gases. A comparison study using two fuels indicates that the trend of temperature distributions obtained by changing the momentum flux ratio is qualitatively similar between hydrogen and methane cases. A quantitative investigation using the relationship between the mixture fraction and temperature suggest that the combustion flow field behind the injector post can be regarded as a non-premixed flame for both hydrogen and methane cases, while there exists some slight deviation from the solutions obtained under a counter-flow flame assumption. The Damköhler number plots help to identify the relationship between flow transport and chemical reaction in the combustion flow fields. The trend of the Damköhler number in the combustion flow fields behind the injector post is quantitatively similar between hydrogen and methane cases. Thus, the present investigation demonstrates that the fuel sensitivity has less impact on the near-field flow and combustion structures of the injector under the conditions used in this study.