Research on blending combustion characteristics of coaxial injector of oxygen/methane engine

Aiming at the demand of oxygen/methane rocket engine for future reusable spacecraft, the design of oxygen/methane coaxial injector engine and the study of flow mixing and combustion characteristics were carried out. The flow field characteristics, flame structure size and heat release state changes under different fuel-oxygen momentum ratio of coaxial injector were investigated. The results show that the increase of fuel-oxygen momentum ratio in the cold flow state increases the influence of the mainstream flow on the flow in the combustion chamber, and the length of the vorticity shear layer also increases. With the increase of fuel-oxygen momentum ratio, the flame's lifting distance gradually decreases, the rate of methane needed to stabilize the flame in the shear layer is over twice that of oxygen. At this time, as this ratio increases, the flame expansion angle increases while its length decreases. Rich combustion in the return zone is suppressed, but there is still some impact on component distribution ahead of main heat release. With the increase of fuel-oxygen momentum ratio, the starting position of the high temperature zone gradually advances, and the increase of fuel-oxygen momentum ratio makes the mainstream temperature change significantly intensified. Within a fuel-oxygen momentum ratio range of 0.5–2, the alteration of this ratio has a significant impact on the temperature profile of the gas close to the wall. However, as the ratio increases, the effect of this change on the gas temperature diminishes significantly.