DIRECT TO PHASE II - Low-Cost Ground Testing for Rotating Detonation Concepts

Navy SBIR 24.2 - Topic N242-D06
NAVAIR - Naval Air Systems Command
Pre-release 4/17/24   Opened to accept proposals 5/15/24   Closes 6/12/24 12:00pm ET

N242-D06 TITLE: DIRECT TO PHASE II: Low-Cost Ground Testing for Rotating Detonation Concepts

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials; Hypersonics; Space Technology

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: Demonstrate a rapid, repeatable, low-cost ground testing solution for rotating detonation engines and combustors to mature hypersonic candidate propellants and fuels from TRL 25.

DESCRIPTION: Hypersonic operating environments are particularly challenging environments to simulate. Often testing approaches are limited to a subset of the representative environment for short durations, and extrapolation is challenging [Ref 1]. Expense and access to current testing facilities limit capacity to capture relevant data and increase schedule timelines for development. This further exacerbates the challenge of predicting design behavior for materials, components, and system performance. The Navy requires a solution to meet the growing cadence of investment in hypersonic weapons technology by near-peers [Refs 24]. A low-cost ground testing solution will spark a leap forward by enabling engineers and scientists to quickly verify and validate assumptions.

The Rotating Detonation Engine (RDE), a specific implementation of the detonation process, appears as 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. There has been a significant increase in laboratory demonstrators with different fuels, injection techniques, operating conditions, dimensions, and geometric configurations. Rocket RDEs have been reported and demonstrated in Japan and Poland [Ref 5]. Understanding the fundamentals of detonation dynamics and interrelated optimizations of device components are critical to demonstrating a promising system.

The Navy requires a rapid, repeatable setup/instrumentation, including standard interface architecture. The flowfield in the hypersonic regime is dominated by certain physical phenomena. Accurate modeling of hypersonic flow requires challenging test campaigns that may not capture the entire flight regime. The complex aerodynamic and aerothermal requirements make adequate test-section size and duration essential for reliable results and model validation [Ref 6]. There is a desire to allow for efficient combination of test data between other facilities, including large test and evaluation facilities currently being constructed [Ref 7]. This Direct to Phase II effort will consist of a 12 month design and prototype fabrication. The Phase II option, if exercised, will install and commission the ground test capability at Naval Air Warfare Center Weapons Division (NAWCWD).

Related S&T efforts in this area are measurement techniques to characterize detonation structure, injection dynamics, mixing characterization, flowfield velocity, and so forth. Additionally, research into surrogate models making use of sparse experimental data sets to predict performance over the system operational map explore the gap this solution is expected to fill by providing additional data to these sparse models. Some of these efforts include [Refs 811].

This rapid low-cost ground test solution will:

1. demonstrate test durations of 0.53 s (threshold) after achieving steady-state:

(a) at this time, it is believed that a realistic time to reach operating conditions will take 520 s with a vitiated heater (using a hot-gas divert valve) prior to combustion initiation. An electric heater may be used. The vitiated heater time to reach operating conditions is included as an example of current understanding and,

(b) a threshold of 30 min between each change in system configuration is expected. It is desired to reach an objective of 15 min from test stop, system change (including air-supply or oxidizer changes, a different injector installation, etc.), and ready to conduct the next test.

i. If the fuel lot or fuel composition has changed, a larger duration than 30 min is expected.

2. constrain the test section geometrically to fit within a 10 ft (3.05 m) length by 10 ft (3.05 m) width by 10 ft (3.05 m) height volume. Supporting hardware, including torches, electric heaters, air compressors and surge tanks, are not included within the volume constraint,

(a) an existing facility has been identified for installation and the volume constraint is intended to protect facility, operators, and transients, and

(b) plume length is not included in the volume constraint, and

3. additional ability to modify test section geometry during testing would be seen positively.

The test solution will be designed with the experimenter in mind. NAWCWD scientists and engineers should be able to instrument the prototype with sufficient measurement capability to inform validation efforts and future effort expenditures on air-breathing rotating detonation engines. Some of the objective measurement capability desires include:

1. providing high-speed pressure (including dynamic) axially and radially over the combustor at a threshold sampling frequency of 1-MHz,

2. providing temperature profiles axially and radially over the combustor

3. load sensor(s) allowing for uninstalled thrust performance measurements, and

4. high-speed video of an optically accessible chamber. The final frame rate will be dependent upon the optical parameters selected to observe the combustion phenomena,

(a) Velocimetry measurements of the flowfield are desired. Ref 11 presents an ideal setup allowing validation of CFD predictions of the flowfield measurements.

5. high-speed chemiluminescence, particularly of OH* for hydrogen, is widely used because it allows for flowfield investigation, detonation height, wave number, and their associated effects on detonation, including entrainment of hot gasses or saturation,

6. shadowgraph/schlieren capability, and

7. laser absorption spectroscopy and/or FTIR at the injection sites and adjustable to capture a representative area in the combustor.

(a) Time-resolved measurements of at least H2O, CO2, and CO concentrations.

Text removed: Demonstrate sufficient measurement capability to inform validation efforts and future effort expenditure on new technologies by:

Velocimetry measurements of the flowfield are desired. Reference 11 presents an ideal setup allowing validation of computational fluid dynamics (CFD) predictions of the flowfield measurements.

Cost-savings (i.e., low cost) is expected from the rapid cadence this system will provide, including its long duration.

PHASE I: For a Direct to Phase II topic, the Government expects that the small business would have accomplished the following in a Phase I-type effort and developed a concept for a workable prototype or design to address, at a minimum, the basic requirements of the stated objective above. The below actions would be required to satisfy the requirements of Phase I:

Design, development, and demonstration of a Preliminary Design of the ground-testing solution will provide solutions for different injection methods, different states (solid, liquid, or gaseous) propellants and fuels, along with associated calculations for safe operation, thrust measurement, and instrumentation. The solution must be designed for interoperability and low life-cycle costs. Subcomponent testing is encouraged. Prototype design and manufacturing plans with estimated cost, including options, should be presented.

FEASIBILITY DOCUMENTATION: Offerors interested in participating in Direct to Phase II must include in their response to this topic Phase I feasibility documentation that substantiates the scientific and technical merit and Phase I feasibility described in Phase I above has been met (i.e., the small business must have performed Phase I-type research and development related to the topic NOT solely based on work performed under prior or ongoing federally funded SBIR/STTR work) and describe the potential commercialization applications. The documentation provided must validate that the proposer has completed development of technology as stated in Phase I above.

PHASE II: Development, fabrication, and verification of a prototype will be demonstrated during the 12 month period for Direct to Phase II. Instrument integration of government-furnished equipment (GFE) will occur prior to testing. Verification testing and prototype acceptance will occur at NAWCWD. Verification will occur via demonstrating retrofit/modification not to exceed one working day to test a solid and liquid fuel and two different injectors (i.e., four tests, two per fuel, in one working day). This verification is not to include data analysis from the test. The system must be fabricated with diagnostic data capture and performance data in mind. The system will be validated by demonstrating sufficient measurement capability to prove and/or disprove computational models of the performed tests.

PHASE III DUAL USE APPLICATIONS: If the Phase II option was not exercised, install and commission the ground test capability at NAWCWD. Additional instrumentation integration of GFE will be a consideration.

The commercial potential of this device lies in the component fabrication and potential secondary applications. The awardee selected contractor will be able to manufacture rotating detonation combustor hardware, and use lessons learned in combustion diagnostic system integration for future advanced propulsion efforts. This system could be used across a broad range of aerospace applications. The low-cost ground-testing system is a product that will be desirable not only for propulsion, but energy production research and development efforts ongoing in RDEs by industry and government agencies, including NASA and Department of Energy.


  1. Losey, Stephen. "ARRW hypersonic missile test failed, US Air Force admits." DefenseNews, 28 March 023.
  2. "Russia test-fires new hypersonic missile from submarine." AP News, 4 October 2021.
  3. "China surprises U.S. with hypersonic missile test, FT reports." Reuters, 17 October 2021. 10-17/
  4. Zhang, Yunzhen; Zhaohua Sheng, Zhaohua; Rong, Guangyao ; Dawen Shen, Dawen; Wu, Kevin; and Wang, Jianping. "Experimental research on the performance of hollow and annular rotating detonation engines with nozzles." Elsevier. Journal of Applied Thermal Engineering, 20 September 2022.
  5. Le Naour, Bruno; Davidenko, Dmitry; Gaillard, Thomas and Vidal, Pierre. "Rotating detonation combustors for propulsion: Some fundamental, numerical, and experimental aspects." Frontiers in Aerospace Engineering. 30 March 2023.
  6. Aeronautics and Space Engineering Board, Commission on Engineering and Technical Systems. "Aeronautical Facilities: Assessing the National Plan for Aeronautical Ground Test Facilities, Chapter 5: Hypersonic Facilities." National Academies Press, 1994.
  7. Socha, Evamarie. "Purdue Applied Research Institute opens $41M Hypersonics and Applied Research Facility." Purdue University, 7 June 2023.
  8. Chacon, F. and Gamba, M. "Study of parasitic combustion in an optically accessible continuous wave rotating detonation engine." AIAA Scitech 2019 Forum, p. 0473.
  9. Gaetano, A. R.; Anand, V.; Betancourt, J. J.; Pritschau, T. C.; Wiggins, R.; Shaw, V. G. and Gutmark, E. "Tomographic Imaging of Rotating Detonations in a Hollow Combustor." AIAA Propulsion and Energy 2021 Forum, p. 3653
  10. Prakash, S.; Klarkowski, C. and Raman, V. "Multi-fidelity modeling-based estimation of rotating detonation engine performance." AIAA SCITECH 2022 Forum, p. 0641.
  11. Dunn, I. B.; Sosa, J.; Salvadori, M.; Ahmed, K. A. and Menon, S. "Flowfield velocity measurements of a rotating detonation engine." AIAA Scitech 2020 Forum, p. 1176.

KEYWORDS: rotating detonation; detonation cells; injector design; propulsion; fuel; ground testing


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