Flow and combustion mechanism of oblique detonation engines

Oblique detonation engine is a novel type of ram propulsion system employed in air-breathing hypersonic flight vehicle. It utilizes oblique detonation waves to achieve the high-efficient combustion in supersonic flow. Benefiting from the scientific and technological advantages such as rapid energy release, high specific impulse, short combustor and fewer moving parts, research on the oblique detonation engines becomes the frontier of hypersonic propulsion technologies. To initiate and adjust the wave structures of the oblique detonations, it is critical to conduct systematic investigation on flow and combustion mechanism in the engine combustors. Due to the coupling of shock waves and combustion, the initiation zone of oblique detonations has the feature of complicated multi-wave structures, which are affected by the properties of the mixtures. Furthermore, these structures are constrained to the wedge by the high speed inflow, very sensitive to the change of inflow parameters. Hence, research on the related unsteady processes is also critical. Finally, the oblique detonation waves in confined spaces involve the interaction of the shock waves and the geometry structures, which is an unavoidable problem in the engineering application. In this paper, research progress of the above aspects has been summarized and commented, clarifying the underlying problems in the application and pointing out the future research trends.