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

OUSW (R&E) CRITICAL TECHNOLOGY AREA(S): Scaled Hypersonics (SHY)

COMPONENT TECHNOLOGY PRIORITY AREA(S): Advanced Materials;Hypersonics

PROJECTED CMMC LEVEL REQUIREMENT: Level 2 (Self)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

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. This SBIR topic focuses on developing a throttleable solid-fuel rotating detonation ramjet (SFRDE) system, enabling dynamic adjustments to a coupled gas generator to enable optimal performance across a wide range of mission profiles.

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 [Refs 1, 2]. 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 design of the gas generator is also crucial to provide a mixture adequate for sustained detonability and coupling with the RDE inlet. Recent studies have demonstrated the viability integration of solid propellants and rotating detonation engines through the use of gas generators [Ref 3]. The proposed research should address the following two key areas to achieve a throttleable SFRDE:

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. Additional considerations should include the selection of appropriate gas generator propellants based on performance, stability, and safety considerations, as well as consideration of ignition methods suitable for the gas generator.

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. Design considerations should include injector geometry and placement to promote rapid mixing and flame stabilization; chamber geometry to facilitate detonation wave initiation and propagation; and thermal management strategies for both the gas generator and combustion chamber.

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. The subscale should trace directly to the conceptual design and planning for tactical-scale prototype to be developed under Phase II.

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 tactical prototype shall reflect the geometry and functionality of an operational system but is not required to be flight-weight. The ground-test campaign nominally will characterize performance across throttle settings, including thrust, specific impulse, combustion efficiency, and response time. If a limited ground test campaign is conducted, data collected should provide sufficient information to validate system-level performance models to assess the SFRDE’s impact on overall ramjet cycle performance. 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. These demonstrations shall be conducted via ground test facilities at simulated ramjet operating conditions. 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. Awardee(s) should improve manufacturing readiness assessments and cost estimates provided during Phase II.

The commercial potential of this device lies in the component fabrication and potential secondary applications. The development of rotating detonation combustor hardware, and lessons learned in combustion diagnostic system integration will be directly applicable to future advanced solid-fuel propulsion system efforts. 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.

REFERENCES:

1. Smirnov, N. N.; Nikitin, V. F.; Stamov, L. I.; Mikhalchenko, E. V. and Tyurenkova, V. V. "Rotating detonation in a ramjet engine three-dimensional modeling." Aerospace Science and Technology, 81, October 2018, pp. 213-224. https://www.sciencedirect.com/science/article/abs/pii/S1270963818316924
2. Liu, S. Liu, W. Wang, Y. and Lin, Z. "Free jet test of continuous rotating detonation ramjet engine." 21st AIAA International Space Planes and Hypersonics Technologies Conference, 2 March 2017, p. 2282. https://arc.aiaa.org/doi/abs/10.2514/6.2017-2282 https://doi.org/10.2514/6.2017-2282
3. Wu, W.; Wang, Y.; Han, W.; Wang, G.; Zhang, M. and Wang, J. "Experimental research on solid fuel pre-combustion rotating detonation engine." Acta Astronautica, 205, April 2023, pp.258-266. https://www.sciencedirect.com/science/article/abs/pii/S0094576523000620

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

TPOC 1
Eric Marineau
eric.c.marineau.civ@us.navy.mil

TPOC 2
Jonathan Sosa
jonathan.sosa4.civ@us.navy.mil

TPOC 3
Collin Overall
collin.r.overall.civ@us.navy.mil