Proper Flowpath Configurations of Circular Scramjet Combustor for High-Performance Propulsion

The flowpath configuration of a scramjet combustor decisively governs its combustion performance. Scramjet combustors are generally classified into rectangular and circular cross-section types. For circular cross-section combustors, numerous flowpath configurations have been proposed worldwide, accompanied by extensive numerical simulations and experimental investigations. This paper systematically reviews proper flowpath configurations for circular cross-section scramjet combustors. It first discusses wall configurations, then examines cavity flameholders, strut flameholders, and other flowpath arrangements. Key geometrical parameters, including wall shape, cavity geometry, strut layout, and their coupling effects, are considered. The influences of these configurations on combustor performance are briefly analyzed, with particular attention to fuel mixing, flame stabilization, and combustion efficiency. Finally, the current research status of circular scramjet combustor geometric design is summarized, and future development prospects are outlined. By consolidating existing knowledge and identifying remaining challenges, this review aims to provide a useful reference for the optimal design of circular cross-section scramjet combustors and to support further advances in high-performance propulsion systems.