DON26BZ01-NV036 — Solid-Fuel Rotating Detonation Ramjet (SF-RDR) for High-Speed Propulsion

Award Maximum: $140,000 (Base) / $100,000 (Option) Period of Performance: 6 months (Base) + 6 months (Option) Phase Type: Phase I

OBJECTIVE: Develop a throttleable solid-fuel Rotating Detonation Ramjet Engine (SFRDE) system by integrating a controllable gas generator to precisely regulate fuel supply, enabling stable and efficient Rotating Detonation Engine (RDE) operation.

DESCRIPTION: The Department of Navy (DON) seeks innovative solid-fuel detonation-based propulsion solutions that can deliver superior performance and operational flexibility. The RDE is a promising candidate to replace current constant-pressure combustion systems, due to its high-thermal efficiency, wide-operating Mach range, short combustion time, and small volume. However, to fully realize the benefits of an RDE for naval applications, particularly in the context of ramjet operation, the ability to operate an RDE on solid fuels and precisely control thrust output is crucial.

To date, RDEs have been demonstrated to operate at ramjet relevant conditions; however, the applicability of RDEs to ramjet cycles has largely focused on the use of gaseous or liquid fuels. The use of solid fuels in RDEs presents additional complexities. Fuel formulations must be carefully tailored to provide detonable fuel at ramjet relevant temperatures. The use of a gas generator to provide the combustible mixture could potentially lead to solid particles clogging the fuel injectors.

The proposed research should address the following two key areas to achieve a throttleable SFRDE: (1) Throttleable Gas Generator Development — Design and develop a compact, lightweight, and throttleable gas generator capable of precisely controlling the flow rate and composition of the fuel and/or oxidizer supplied to the RDE; (2) Combustion Chamber Design — Optimize the rotating detonation engine combustion chamber design for stable rotating detonation wave propagation and efficient mixing of the gas generator's output with the primary oxidizer stream.

PHASE I: Design, develop, and demonstrate: (1) a throttleable gas generator subsystem and (2) that the gas generator provides a combustible mixture detonable at ramjet relevant temperatures. Solutions are preferred that are capable of demonstrating a subscale SFRDE system with the throttleable gas generator. Demonstrations should achieve sustained detonation operation for nominal durations of 0.5 to 3.0 seconds after reaching steady state.

PHASE II: Develop and fabricate a tactical-scale prototype of a throttleable SFRDE. Performance and operation will be demonstrated under ramjet-relevant conditions during ground-test. The ground-test campaign nominally will characterize performance across throttle settings, including thrust, specific impulse, combustion efficiency, and response time. Awardee(s) should provide a manufacturing readiness assessments and initial cost estimates of Low-Rate Initial Production (LRIP).

PHASE III DUAL USE APPLICATIONS: Further improve the SFRDE system and expand on the experimental demonstration for Navy-relevant conditions and vehicle geometries. If supported by transition partners, Phase III may include development of flight-representative hardware or subcomponents and associated validation for integration into a future flight demonstration. The commercial potential of this device lies in the component fabrication and potential secondary applications. The sub-systems and technologies developed could be used across a broad range of power-generation, thermal management, and aerospace applications. The system has applicability to energy production research and development efforts ongoing in RDEs by industry and government agencies, including NASA and the Department of Energy.

KEYWORDS: Solid Fuel; Rotating Detonation Engine; Gas Generator; Detonation; High-Speed Propulsion; Ramjet