High flowrate injector with gaseous hydrogen and gaseous oxygen

In order to get a high flowrate gas-gas injector and its design methodology, the combustion flow field of a typical shear-coaxial injector was analyzed firstly. The dimensional analysis was applied in the phenomenon of gas-gas combustion, and design parameter optimization and a structure improvement were also carried out. A high flowrate single-element injector with high H₂/O₂ momentum ratio and tapered O₂ post tip was obtained and validated by both numerical and experimental studies. This high flowrate injector has simple construction and it can effectively enhance the mixing, decrease the combustion completion length and also has a benign heat environment. Furthermore, based on the study on the single-element injector, numerical optimization and validation experiments were conducted successively on multi-element injector equipped with high flowrate injection elements. The multi-element injector with the high flowrate elements operated steadily, started up and shut down smoothly without any stability aids. In the combustor designed with nominal parameters, this injection element can obtain high combustion efficiency in the flowrate of 3.7 times that of SSME main injector element and shows a benign chamber wall heat compatibility. This injector design and the design methodology can become a reference for design of other kind of injectors in Liquid Rocket Engines.