Progress and challenges in exploration of powder fueled ramjets

Abstract

• A detailed review of the research progress on powder fueled ramjets is presented. • The key technologies and scientific issues in powder fueled ramjets are proposed. • Some suggestions are proposed for the development of powder fueled ramjets. The powder fueled ramjet is a developing propulsion system, which makes use of metal powder as the propellant and presents noticeable advantages, for instance, high specific impulse and density-specific impulse, thrust adjustment, simple structure, and suitability for high Mach flight vehicles. In this paper, the basic work characteristics are introduced and the exploration progress is reviewed and summarized for powder fueled ramjets. Furthermore, several key technologies are proposed, which mainly include the powder feeding system, ignition and combustion processes of the powder fuel, combustion organization technology, multiple start, thrust adjustment, and thermal protection technology. The development of the powder fueled ramjet is in the proof-of-concept stage, and a large number of individual technology breakthroughs have been achieved in subsonic conditions. However, in both subsonic and supersonic conditions, the combustion mechanism of powder fuel needs to be investigated by high precision gas–solid two-phase numerical simulation methods, and ground tests, thus, to guide combustion chamber design. In order to achieve thrust regulation, coupling studies on powder fuel delivery and combustion are required. Besides, new thermal protection schemes based on the lattice structural and supercritical fluid active cooling have great potential to meet the demands of complicated two-phase combustion thermal environments.