Plasma-Assisted Combustion to Enhance the Performance and Operability of RDCs for Naval Applications

Ever-increasing mission requirement intensity calls for advancements in Navy vehicle capabilities. These vehicles need to exceed the capabilities of U.S. adversaries, which requires increased range and speed while decreasing inert weight and volume. To achieve these goals, advancements in vehicle propulsion systems are required. In addition, autonomous and collaborative combat vehicles present new mission requirements and vehicle constraints. This is especially true for augmentors on small Navy vehicles such as unmanned aircraft since the length of these combustion devices does not scale down with engine diameter. Conventional augmentors cannot be used on small-diameter engines due to the extra weight required. In addition, conventional flame stabilization features incur total pressure loss even when the augmentor is not operating. One potential solution is to utilize rotating detonation combustion in the augmentor in place of conventional constant-pressure combustion. Rotating detonation combustors can provide multiple benefits over their constant-pressure counterparts in propulsion applications. Their simple mechanical design eliminates complex structures that, while required to anchor the flame, can also incur total pressure losses. Detonation-based combustors also have a decreased combustor volume requirement which reduce system weight and improve packaging. Finally, they have the potential to have a performance increase over deflagrative combustion. To address operability challenges that rotating detonation combustion has faced in past studies, plasma generation can be used to improve kinetic rates through the generation of electrons and ions in regimes where augmentors are expected to operate (low oxygen content, combustion products, cooler duct air, etc.).  In order to further develop the technology readiness level of the rotating detonation augmentor, a full-scale prototype combustor will be designed, fabricated, and tested at conditions relevant to flight missions for unmanned aircraft. This includes operating with both a clean “duct” flow and a vitiated “core” flow to represent the operation of the augmentor in a direct-connect facility. Tunable operating parameters, geometric features, and plasma discharge characteristics will be investigated. The experimental results will be used to tune an updated cycle and system analysis in order to predict performance at various points in a mission profile, which will determine the engineering requirements for a flight-ready plasma generation system and rotating detonation augmentor design.