by Douglas Messier
Managing Editor
NASA has selected projects for funding by Masten Space Systems and Spectral Energies that are focused on developing technology for advanced rotating detonation rocket engines (RDE).
The space agency selected the companies for Small Business Innovation Research (SBIR) Phase I awards that are worth up to $150,000 apiece. Masten and Spectral Energies are both working on high-performance injector systems.
A RDE uses one or more detonations that continuously travel around an annular channel at supersonic speed. RDE engines could be as much as 25 percent more efficient than existing rocket engines. Challenges include combustion instability and noise.
“The proposed innovations are as follows: 1. rotating detonation engine (RDE) injector using Masten’s patent-pending permeable additive manufacturing (PermiAM) method, which provides improved propellant distribution and cooling in the engine relative to traditional injector methods; 2. liquid-liquid injector using liquid oxygen (LOX)/methane; [and] the ability to manufacture single parts with varying material properties will enable cost savings in areas where, in the past, multiple components required manufacturing and assembly with a high touch time,” Masten said in its proposal summary.
Spectral Energies said its project “will include the development of validated accurate rules and tools that can be used for designing ultra-high-performance RDRE injectors, and the knowledge regarding injector design, detonation combustion, and global performance. It will provide NASA an experimental dataset to anchor future modeling and simulations and engine development efforts.
“Non-NASA applications of the proposed efforts include ultra-high-performance injectors for air-breathing and rocket rotating detonation engines (e.g., DoD, DoE). Commercial applications include air-breathing propulsion, stationary power generation, and fundamental research in a wide range of aerothermal flows,” Spectral Energies said.
Summaries of the Masten and Spectral Energies proposals are reproduced at the end of this article.
Masten and Spectral Energies are not the only companies conducting work on RDEs. Venus Aerospace of Houston recently unveiled plans for a hypersonic aircraft that would travel at Mach 9. The aircraft would take off using conventional jet engines and then transition to RDE propulsion.
Aerojet Rocketdyne began testing RDE configurations in 2010. The company has conducted 520 tests of various configurations.
In March 2022, the U.S. Air Force Research Laboratory awarded Pratt & Whitney a contract to demonstrate a RDE. The company is working with Raytheon Missiles & Defense and Raytheon Technologies Research Center to develop the engine.
In 2020, an engineering team from the University of Central Florida said it had developed an experimental RDE capable of producing 200 lbf (~890 N) of trust using a hydrogen and oxygen as fuel. The group was affiliated with the U.S. Air Force.
China is developing a RDE capable of accelerating aircraft and missiles to Mach 5 (6,174 km/h – 3,836 mph) or faster. There is great concern at the Pentagon that the United States has fallen behind China and Russia in hypersonic missiles.
NPO Energomash of Russia is reported to have completed the initial test phase of a two-metric ton class RDE in January 2018. The company planned to develop larger engine variants for use in launch vehicles.
The Japan Aerospace Exploration Agency (JAXA) said it successfully tested a RDE in space for the first time aboard a S-520-31 sounding rocket on July 26, 2021. The RDE was installed on the booster’s second stage.
The Warsaw Institute of Aviation reported the successful test of a RDE aboard a rocket on Sept. 15, 2021. The engine worked for 3.2 seconds, accelerating the rocket to 90 m/s (324 km/h or 201 mph).
Rotating Detonation Engine Novel Injector Design
Subtopic Title: Rotating Detonation Rocket Engines (RDRE)
SBIR Phase I: up to $150,000
Masten Space Systems, Inc.
Mojave, Calif.
Principal Investigator: David Masten
Estimated Technology Readiness Level (TRL):
Begin: 3
End: 4
Duration: 6 months
Technical Abstract
The proposed innovations are as follows:
- Rotating detonation engine (RDE) injector using Masten’s patent-pending permeable additive manufacturing (PermiAM) method, which provides improved propellant distribution and cooling in the engine relative to traditional injector methods.
- Liquid-liquid injector using liquid oxygen (LOX)/Methane.
- The ability to manufacture single parts with varying material properties will enable cost savings in areas where, in the past, multiple components required manufacturing and assembly with a high touch time. Masten has demonstrated a cost reduction of 60% in past injector builds.
Success of this SBIR project will be indicated by the construction and testing of two PermiAM RDE injectors. The three phases of this project are: design, manufacture, and testing. This SBIR will provide valuable information for several existing questions relating to RDE research. How to design a flight like liquid/liquid detonation engine, and how to design an injector capable of handling the extreme temperature and pressure environments.
Potential NASA Applications
RDE’s have the inherent advantage of being theoretically more efficient than standard combustion engines. This is due to the detonation engine utilizing a Humphrey cycle over a Brayton cycle. A Humphrey cycle is a constant volume cycle, where a Brayton cycle is constant pressure.
Potential Non-NASA Applications
In a perfect system a RDE has the potential to be about 15% more efficient than that of a constant pressure device. The ability to utilize this kind of increase would be invaluable in commercial application, where fuel consumption can be a major driver in cost.
Optimization of Multiphase Injector Dynamics for Rotating Detonation Rocket Engines
Subtopic Title: Rotating Detonation Rocket Engines (RDRE)
SBIR Phase I: up to $150,000
Spectral Energies
Dayton, Ohio
Principal Investigator: Dr. Christopher Fugger
Estimated Technology Readiness Level (TRL):
Begin: 3
End: 4
Technical Abstract
Designing an ultra-high-performance Rotating Detonation Rocket Engine (RDRE) is challenging due to the lack of in-depth understanding of many key mixing and combustion processes. The design of ultra-high-performance RDRE injectors requires improved understanding of how the injector design affects its response and performance under the highly unsteady and impulsive detonation environment.
These injectors must be optimized for
(i) the ability to improve and control gaseous and liquid injector diodicity, while also minimizing the forward direction injector pressure drop to improve overall system performance,
(ii) the ability to optimize the relative injector response and recovery of the fuel and oxidizer to achieve the desired mixture ratio and minimize deflagration losses, and
(iii) the ability to control the mixing rate to ensure reliable detonation at the ideal lift-off position.
The proposed research effort will develop ultra-high-performance injector solutions that meet these requirements.
High performance injectors will be evaluated at multiple fidelity levels with multidisciplinary design optimization combined with Unsteady Reynolds-Averaged Navier Stokes modeling and simulation for design optimization of diode injectors. Concurrently, injector concepts will be designed and experimentally tested and evaluated under cold-flow and hot-fire RDE conditions.
The Phase 1 goals are twofold:
(1) design, test, and evaluate high diodicity single-element monophase and multi-element multiphase injectors in cold flow and hot-fire RDE experiments, with the CFD design optimization driving some of the injector concepts, and
(2) initiating the development of a design methodology that is supported by CFD optimization and experimental validation.
These steps will guide the transition and development in the Phase II of (i) multi-element injection behavior and (ii) larger-scale injector concepts to be evaluated initially in a high-pressure oxygen-rich preburner GOx-liquid RP RDRE.
Potential NASA Applications
The proposed work seeks to develop ultra-high-performance injector solutions for RDREs. This will include the development of validated accurate rules and tools that can be used for designing ultra-high-performance RDRE injectors, and the knowledge regarding injector design, detonation combustion, and global performance. It will provide NASA an experimental dataset to anchor future modeling and simulations and engine development efforts.
Potential Non-NASA Applications
Non-NASA applications of the proposed efforts include ultra-high-performance injectors for air-breathing and rocket rotating detonation engines (e.g., DoD, DoE). Commercial applications include air-breathing propulsion, stationary power generation, and fundamental research in a wide range of aerothermal flows.
