Rotating detonation engine

The basic concept of an RDE is a detonation wave that travels around a circular channel (annulus). Fuel and oxidizer are injected into the channel, normally through small holes or slits. A detonation is initiated in the fuel/oxidizer mixture by some form of igniter. After the engine is started, the detonations are self-sustaining. One detonation ignites the fuel/oxidizer mixture, which releases the energy necessary to sustain the detonation. The combustion products expand out of the channel and are pushed out of the channel by the incoming fuel and oxidizer.

Although the RDE's design is similar to the pulse detonation engine (PDE), the RDE can function continuously because the waves cycle around the chamber, while the PDE requires the chambers to be purged after each pulse.{{Cite web |title=Pressure Gain Combustion Program Committee - Resources|first1=Mark|last1=Fernelius|first2=Shareil|last2= Elia|first3=Dora E. |last3=Musielak |url=https://info.aiaa.org/tac/pc/PGCPC/Resources/Resources.aspx |url-status=dead |archive-url=https://web.archive.org/web/20170101000924/https://info.aiaa.org/tac/pc/PGCPC/Resources/Resources.aspx |archive-date=2017-01-01 |accessdate=2016-12-30 |website=AIAA Pressure Gain Combustion Program Committee}}

Several organizations work on RDEs.

In 2023 GE Aerospace demonstrated a subscale laboratory turbine based combined cycle (TBCC) system that combined a Mach 2.5-class turbofan paired with a rotating detonation-dual-mode ramjet (RD-DMRJ). The test came 18 months after program launch. The company reported rotating detonations of a compressed fuel-air mixture in the presence of the supersonic airflow necessary for speeds above Mach 5.{{Cite web |last=Trimble |first=Steve |date=December 19, 2023 |title=Rotating Detonation Sparks GE Path To Hypersonic Future {{!}} Aviation Week Network |url=https://aviationweek.com/aerospace/aircraft-propulsion/rotating-detonation-sparks-ge-path-hypersonic-future |access-date=2023-12-22 |website=aviationweek.com}}

DARPA is working with RTX on Gambit, researching the application of rotating detonation engines for supersonic air-launched standoff missiles.{{Cite web |title=Gambit |url=https://www.darpa.mil/program/gambit |first=Buccellato|last=Salvatore|accessdate=2023-12-03|website=darpa.mil}}{{Cite web |title=RTX to develop rotating detonation engine for DARPA |url=https://www.rtx.com/news/news-center/2023/10/04/rtx-to-develop-rotating-detonation-engine-for-darpa |accessdate=2023-12-03}} DARPA is also working with Venus Aerospace which successfully tested its RDRE engine in March 2024.{{Cite web |last=Szondy |first=David |date=March 11, 2024 |title=Video: Hypersonic rotating detonation engine in sustained test burn |url=https://newatlas.com/military/rotating-detonation-engine/ |access-date=2024-04-04 |website=New Atlas }}

The US Navy has been pushing development.{{Cite web |date=2013-03-08 |title=How the Rotating Detonation Engine Works |url=http://auto.howstuffworks.com/under-the-hood/trends-innovations/rotating-detonation-engine3.htm|last1=Threewitt|first1=Cherise|website=HowStuffWorks}} Researchers at the Naval Research Laboratory (NRL) have a particular interest in the capability of detonation engines such as the RDE to reduce the fuel consumption of their ships.{{Cite journal |date=2012-11-06 |title=US Navy developing rotating detonation engine|first1=Kyle|last1=Niemeyer |url=http://scitation.aip.org/content/aip/magazine/physicstoday/news/news-picks/usnvydevelopingrottingdetontionengine-a-news-pick-post |journal=Physics Today |doi=10.1063/PT.5.026505 |issn=0031-9228}}{{dead link|date=November 2023}} Several obstacles must still be overcome in order to use the RDE in the field. As of 2012, NRL researchers were focusing on better understanding how the RDE works.{{Cite web |title=Navy Researchers Look to Rotating Detonation Engines to Power the Future |url=https://www.nrl.navy.mil/Media/News/Article/2565333/navy-researchers-look-to-rotating-detonation-engines-to-power-the-future/ |first1=Donna|last1=McKinney| accessdate=2022-03-14 |website=U.S. Naval Research Laboratory}}

Since 2010, Aerojet Rocketdyne has conducted over 520 tests of multiple configurations.{{cite web |last1=Claflin |first1=Scott |display-authors=etal|title=Recent Advances in Power Cycles Using Rotating Detonation Engines with Subcritical and Supercritical CO2 |url=http://www.swri.org/4org/d18/sCO2/papers2014/systemConcepts/09PPT-Claflin.pdf |url-status=dead |archive-url=https://web.archive.org/web/20170320150236/http://www.swri.org/4org/d18/sCO2/papers2014/systemConcepts/09PPT-Claflin.pdf |archive-date=20 March 2017 |accessdate=20 March 2017 |website=Southwest Research Institute|s2cid=161054165}}

Daniel Paxson{{Cite web |title=Daniel E. Paxson - Controls and Dynamics Branch Personnel |url=https://www.grc.nasa.gov/WWW/cdtb/personnel/dan.html |url-status=dead |archive-url=https://web.archive.org/web/19990823161712/http://www.grc.nasa.gov/WWW/cdtb/personnel/dan.html |archive-date=1999-08-23 |access-date=2020-02-20 |website=www.grc.nasa.gov}} at the Glenn Research Center used simulations in computational fluid dynamics (CFD) to assess the RDE's detonation frame of reference and compare performance with the PDE.{{Cite web |title=UCSB Full Bib - External Link |url=http://pegasus.library.ucsb.edu/F/MBE5776HMPFJMQ45D8TAUSM6V9237AU4DVN1D521M49XLCE8CG-35036?func=service&doc_library=SBA01&doc_number=004533761&line_number=0001&func_code=WEB-FULL&service_type=MEDIA |archive-url=https://web.archive.org/web/20220827224623/http://pegasus.library.ucsb.edu/F/MBE5776HMPFJMQ45D8TAUSM6V9237AU4DVN1D521M49XLCE8CG-35036?func=service&doc_library=SBA01&doc_number=004533761&line_number=0001&func_code=WEB-FULL&service_type=MEDIA |url-status=dead |archive-date=August 27, 2022 |accessdate=2015-11-09 |website=pegasus.library.ucsb.edu}} He found that an RDE can perform at least on the same level as a PDE. Furthermore, he found that RDE performance can be directly compared to the PDE as their performance was essentially the same.

On January 25, 2023, NASA reported successfully testing its first full-scale rotating detonation rocket engine (RDRE). This engine produced {{cvt|4,000|lbf|kN}} of thrust. NASA has stated their intention to create a {{convert|10,000|lbf|kN|adj=on}} thrust unit as the next research step.{{Cite web |title=NASA Validates Revolutionary Propulsion Design for Deep Space Missions|first1=Ray|last1=Osorio |url=https://www.nasa.gov/centers/marshall/feature/nasa-validates-revolutionary-propulsion-design-for-deep-space-missions |access-date=2023-01-26 |website=www.nasa.gov|date=25 January 2023 }} On December 20, 2023, a full-scale Rotating Detonation Rocket Engine combustor was reportedly fired for 251 seconds, achieving more than {{convert|5,800|lbf|kN|adj=on}} of thrust. Test stand video captured at NASA's Marshall Space Flight Center in Huntsville, Alabama, US, demonstrated ignition.{{Cite web |title=NASA's 3D-printed Rotating Detonation Rocket Engine Test |url=https://www.nasa.gov/centers-and-facilities/marshall/nasas-3d-printed-rotating-detonation-rocket-engine-test-a-success/ |access-date=2023-12-21 |website=www.nasa.gov|date=20 December 2023|first1=Raymond J|last1=Osorio }}

According to Russian Vice Prime Minister Dmitry Rogozin, in mid-January 2018 NPO Energomash company completed the initial test phase of a 2-ton class liquid propellant RDE and plans to develop larger models for use in space launch vehicles.{{Cite web |title=Facebook |url=https://www.facebook.com/dmitry.rogozin/posts/1651863201503679?pnref=story |access-date=2023-12-22 |website=www.facebook.com}}{{dead link|date=January 2024}}

In May 2016, a team of researchers affiliated with the US Air Force developed a rotating detonation rocket engine operating with liquid oxygen and natural gas as propellants.{{YouTube|pHcxI-8GtZg|Purdue LOX/NG RDE - HotFire}} Additional RDE testing was conducted at Purdue University, including a test article called "Detonation Rig for Optical, Non-intrusive Experimental measurements (DRONE)", an "unwrapped" semi-bounded, linear detonation channel experiment.{{cite web |last=Slabaugh |first=Carson |date=2018 |title=Advancing Pressure Gain Combustion in Terrestrial Turbine Systems |url=https://netl.doe.gov/sites/default/files/netl-file/Carson-Slabaugh-Track-A.pdf |access-date=5 November 2022 |website=netl.doe.gov |publisher=Department of Energy}} IN Space LLC, in a contract with the US Air Force, tested a

{{cvt|22,000|N|lbf|adj=on}} thrust rotating detonation rocket engine (RDRE) while testing with liquid oxygen and gaseous methane at Purdue University in 2021.{{cite web |date=2022 |title=ROTATING DETONATION ROCKET ENGINES (RDRE) |url=https://afresearchlab.com/technology/rotating-detonation-rocket-engines-rdre |access-date=5 November 2022 |website=afresearchlab.com |publisher=Air Force Research Laboratory}}

In May 2020, a team of engineering researchers affiliated with the US Air Force claimed to have developed a highly experimental working model rotating detonation engine capable of producing {{cvt|200|lbf|N}} of thrust operating on a hydrogen/oxygen fuel mix.{{cite web |last1=Blain |first1=Loz |date=5 May 2020 |title=World-first "impossible" rotating detonation engine fires up |url=https://newatlas.com/space/rotating-detonation-engine-ucf-hydrogen-oxygen/ |accessdate=6 May 2020 |website=New Atlas}}

In 2021 the group demonstrated an oblique detonation wave engine with a ramp angle of 30 degrees.{{Cite web |title=UCF Oblique Wave Detonation Engine |url=https://www.infinitymasculine.com/posts/ucf-oblique-wave |access-date=2024-06-07 |website=www.infinitymasculine.com }}{{Cite conference |last1=Thornton |first1=Mason R. |last2=Rosato |first2=Daniel A. |last3=Ahmed |first3=Kareem A. |date=2022-01-03 |title=Experimental Study of Oblique Detonation Waves with Varied Ramp Geometries |url=https://arc.aiaa.org/doi/10.2514/6.2022-1753 |publisher=American Institute of Aeronautics and Astronautics |doi=10.2514/6.2022-1753 |isbn=978-1-62410-631-6 |conference=AIAA SCITECH 2022 Forum 3{{ndash}}7 January 2022 |conference-url=https://arc.aiaa.org/doi/book/10.2514/MSCITECH22 |location=San Diego, CA |access-date=13 November 2024}}

On July 26, 2021 (UTC), Japan Aerospace Exploration Agency (JAXA) succeeded in testing the RDE in space for the first time in the world by launching the S-520-31 sounding rocket equipped with a 500 N class RDE in the second stage.{{Cite web |date=19 August 2021|first1=Florina|last1=Spînu |title=Japan Tests Explosion-Powered Rocket for the First Time in Space, Is a Success |url=https://www.autoevolution.com/news/japan-tests-explosion-powered-rocket-for-the-first-time-in-space-is-a-success-167696.html}} The engine used gaseous methane and oxygen as propellants, generating an average thrust of 518 N and delivering 290 seconds of specific impulse. Rotating combustion also created a torque of 0.26 N·m, so a S-shaped pulse detonation engine was used to reduce the spin of the stage.{{Cite journal |last1=Goto |first1=Keisuke |last2=Matsuoka |first2=Ken |last3=Matsuyama |first3=Koichi |last4=Kawasaki |first4=Akira |last5=Watanabe |first5=Hiroaki |last6=Itouyama |first6=Noboru |last7=Ishihara |first7=Kazuki |last8=Buyakofu |first8=Valentin |last9=Noda |first9=Tomoyuki |last10=Kasahara |first10=Jiro |last11=Matsuo |first11=Akiko |last12=Funaki |first12=Ikkoh |last13=Nakata |first13=Daisuke |last14=Uchiumi |first14=Masaharu |last15=Habu |first15=Hiroto |display-authors=1 |date=2023 |orig-date=2022 |title=Space Flight Demonstration of Rotating Detonation Engine Using Sounding Rocket S-520-31 |journal=Journal of Spacecraft and Rockets |volume=60 |issue=1 |pages=273–285 |doi=10.2514/1.A35401 |bibcode=2023JSpRo..60..273G |issn=0022-4650}}{{Cite conference |last1=Kawasaki |first1=Akira |last2=Matsuyama |first2=Koichi |last3=Matsuoka |first3=Ken |last4=Watanabe |first4=Hiroaki |last5=Itouyama |first5=Noboru |last6=Goto |first6=Keisuke |last7=Ishihara |first7=Kazuki |last8=Buyakofu |first8=Valentin |last9=Noda |first9=Tomoyuki |display-authors=1 |date=January 3–7, 2022 |title=Flight Demonstration of Detonation Engine System Using Sounding Rocket S-520-31: System Design |url=https://arc.aiaa.org/doi/10.2514/6.2022-0229 |conference=AIAA SCITECH 2022 Forum |publisher=American Institute of Aeronautics and Astronautics |doi=10.2514/6.2022-0229 |isbn=978-1-62410-631-6}}

S-520-34 launched on November 14, 2024, experimented successfully with a liquid ethanol / Nitrous oxide propellant.{{cite web |url=https://www.jaxa.jp/press/2024/11/20241114-1_j.html |language=ja |script-title=ja:観測ロケットS-520-34号機実験の実施結果 |publisher=JAXA |date=14 November 2024 |access-date=18 November 2024}}

On September 15, 2021, the Warsaw Institute of Aviation performed the first successful flight test of an experimental rocket powered by a rotating detonation rocket engine, powered by liquid propellants. The test took place on September 15, 2021, at the testing ground of the Military Institute of Armament Technology in Zielonka near Warsaw in Poland. The rocket engine, according to the plan, worked for 3.2 s, accelerating the rocket to a speed of about 90 m/s, which allowed the rocket to reach an altitude of 450 m.{{Citation |title=Poland launched a rocket powered by a detonation engine | date=30 September 2021 |url=https://www.youtube.com/watch?v=bc9JmPlgBy8 |access-date=2021-10-07 }}

In 2023 researchers announced a demonstration unit of a hybrid air-breathing engine. It combines a continuous RDE for propulsion at below Mach 7 with an oblique detonation engine for use at speeds up to Mach 16. The oblique detonation waves are stationary and stabilized. BPMI is China's leading ramjet manufacturer.{{Cite web |last=Wang |first=Brian |date=2023-12-29 |title=China Makes Most Powerful Detonation Engine for Hypersonic Flight {{!}} NextBigFuture.com |url=https://www.nextbigfuture.com/2023/12/china-makes-most-powerful-detonation-engine-for-hypersonic-flight.html |access-date=2023-12-31 }}

Earlier in 2023, China achieved the world's first RDE drone flight. The drone successfully flew at an undisclosed airfield in Gansu province. The FB-1 Rotating Detonation Engine was developed jointly by Chongqing University Industrial Technology Research Institute and private company Thrust-to-Weight Ratio Engine (TWR).

On March 4, 2025, Pratt & Whitney reported they successfully completed tests on their RDE. It was tested in extreme conditions they are looking to operate in, with their eventual goal: to propel “Vehicles critical to future defence applications”. They believe the engine with no moving parts can increase efficiency and cost due to the lower complexity, allowing for more mass to be budgeted in other subsystems, like fuel and payloads.{{Cite web |title=RTX's Pratt & Whitney completes series of rotating detonation engine testing |url=https://www.rtx.com/news/news-center/2025/03/04/rtxs-pratt-whitney-completes-series-of-rotating-detonation-engine-testing |access-date=2025-03-27 |website=United Technologies |language=en}}

Other experiments have used numerical procedures to better understand the flow-field of the RDE.{{Cite journal |last1=Schwer |first1=Douglas |last2=Kailasanath |first2=Kailas |date=2011-01-01 |title=Numerical investigation of the physics of rotating-detonation-engines |journal=Proceedings of the Combustion Institute |volume=33 |issue=2 |pages=2195–2202 |doi=10.1016/j.proci.2010.07.050|bibcode=2011PComI..33.2195S }} In 2020, a study from the University of Washington explored an experimental device that allowed control of parameters such as the width of the annulus. Using a high-speed camera, researchers were able to view it operating in extreme slow motion. Based on that they developed a mathematical model to describe the process.{{Cite web |last=Strickler |first=Jordan |date=February 19, 2020 |title=New detonating engine could make space travel faster and cheaper |url=https://www.zmescience.com/space/space-flight-space/new-detonating-engine-could-make-space-travel-faster-and-cheaper/ |access-date=2020-02-20 |website=ZME Science }}

In 2021, the Institute of Mechanics, Chinese Academy of Sciences, successfully tested the world's first hypersonic detonation wave engine powered by kerosene, which could propel a plane at Mach 9.{{cite web |date=November 20, 2022 |title=China claims 'world's first' kerosene-powered engine could propel jets nine times the speed of sound |first1=Baba|last1=Tamim|url=https://interestingengineering.com/innovation/china-worlds-first-kerosene-powered-engine}}

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• [https://www.youtube.com/watch?v=EBcflqPNhCY Video demonstrating how the RDE works]
• [http://permanent.access.gpo.gov/gpo57039/20140013391.pdf Daniel Paxson's research paper on his findings of the RDE]
• [https://www.youtube.com/watch?v=RVxgyz_avQM Video on the RDE] - Real Engineering

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• {{Cite journal |last=Sun |first=Jie |last2=Yang |first2=Pengfei |last3=Tian |first3=Baolin |last4=Chen |first4=Zheng |date=November 2023 |title=Evolution and Control of Oblique Detonation Wave Structure in Unsteady Inflow |url=https://arc.aiaa.org/doi/10.2514/1.J062809 |journal=AIAA Journal |volume=61 |issue=11 |pages=4808–4820 |doi=10.2514/1.J062809 |issn=0001-1452}}

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