Investigation of mixing and initiation characteristics of oblique detonation engine in confined spaces

The oblique detonation engine (ODE) is a novel air-breathing propulsion system capable of meeting the requirements of hypersonic flight at Mach numbers above 8. In a confined hypersonic flow channel, fuel must achieve mixing within extremely short time and distance constraints to enable reliable initiation and stable standing of an oblique detonation wave (ODW). This study employs two central struts with internal-pressure fuel injection configuration, through two-dimensional numerical simulations investigate the fuel injection mixing characteristics of hydrogen in a confined hypersonic flow channel and the initiation behavior of the ODW. Meanwhile, experimental validation of the oblique detonation initiation is also conducted. The results indicate that under the injection configuration with a 30° angle relative to the axial direction downstream of the central strut, the mixing uniformity of hydrogen fuel reaches 0.63 at a distance of 1060 mm. There is no early combustion in the flow channel, which strongly supports the initiation of ODW. The wedge configuration significantly influences the initiation and standing of the ODW. As the wedge angle increases, the ODW transitions from a smooth type to an abrupt type. Concurrently, the induction distance of the oblique shock wave (OSW) shortens, the position of the ODW moves forward, and the fuel becomes more prone to combustion. Ground ignition tests successfully achieved initiation and standing of the ODW, confirming the rationality of the combustor configuration design. This study guides the structural optimization and reliable combustion organization of ODE combustors. • The mixing uniformity of hydrogen fuel at the inlet of the initiation section (at 1060 mm) can reach 0.63. • The ignition and standing characteristics of oblique detonation waves under different induced wedge angles are revealed. • Ground ignition tests of oblique detonation have verified the rationality of the combustor configuration design.