Rotating detonation engine

A rotating detonation engine (RDE) is a form of pressure gain combustion where one or more detonations continuously travel around an annular channel. Computational simulations and experimental results have shown that the RDE has potential as a method of combustion.[1] Throughout its years of research and development, it is the U.S. military, more specifically, the navy, that have been the most invested in this sort of power. Currently, most gas-turbine engines operate on the Brayton cycle, which is what the RDE is based on. Unfortunately, the only drawback is that the engine cannot be modified to improve the energy output or efficiency.[2] Ideally, the RDE has the capability to increase the performance of military technology by producing a greater amount of power while saving costs on fuel consumption. Further testing of the RDE can be seen by NASA and many accredited researchers.

Patent

Although the patent was awarded on March 26, 1982,[3] as of late 2012 it was realized that the RDE has the potential to generate enough energy to power large modes of transportation such as ships or aircraft. However, the most beneficial use for this engine would be for the US Navy since they use many large commercial vehicles. In fact, the patent of the RDE is accredited to Shmuel Eidelman[4] who has specialized in inventing military technology that focus on chemicals, aeronautics, and propulsion. Since 1982, he has been awarded 14 out of 15 patents by the U.S Patent Office.

How it works

This type of engine functions by combining the air and fuel while being injected into a cylindrical combustion chamber. When the first particle detonates, it immediately sets off a chain reaction in which the energy from the previous ignition travels around the chamber as it subsequently ignites the next sequence. The cycle continues because the pressure from the previous ignition keeps it moving. That pressure then forces the exhaust gas out of the combustion chamber, travel through the exhaust nozzle, and generate thrust. That thrust then powers the vehicle the engine is in, typically a ship or an aircraft. Although the RDE's design is similar to the pulse detonation wave engine (PDE), one aspect that makes the RDE superior is the fact that the waves constantly cycle around the chamber while the PDE requires the chambers to be purged after each pulse.[5] Typically, a detonation engine can be designed without a compressor which are usually complex and absorbs too much energy; however, including a compressor in the RDE would, in fact, make it more efficient. The addition of the compressor would transform the engine to operate into a wider array of vehicles that uses detonation turbine energy, such as a ship or plane.[6][7]

Navy involvement

One particular aspect that makes this engine unique is its ability to be scalable- as the size of the engine increases, its power and energy output will also increase. So it is possible to scale this engine to a small size in order to fit into smaller machinery. The researchers at the Naval Research Laboratory (NRL) have been showing particular interest in detonation engines, specifically the RDE, mainly because they realize these engines have the capability to reduce the fuel consumption in their heavy vehicles. It is known that the U.S Navy currently spends about $2 billion per year on fuel alone. As of today, there are about 430 gas turbine engines on 129 U.S Navy ships. By optimizing those engines with RDE technology, they would be able to increase their engine power capabilities by 10% as well as reduce their fuel consumption by 25%;[8] thus, adding up to an annual savings of $300 - $400 million.[9] Although this can bring about significant fuel efficiency of naval vehicles, several obstacles still remain to overcome in order to use the RDE in the field.[10] NRL researchers are currently focusing on getting a better understanding of how the RDE works and the benefit it can play when in practice.

Current development

Since the RDE still remains an intangible idea, the actual size of the engine model still remain uncertain. However, the navy is promising that they are pushing the development of this engine,[11] but there is no known time of completion. Because this engine only exists in simulation, the actual size model of the engine is still hypothetical and remains in development.

Experiments

Researchers at NASA also play a part in the development of the RDE. Daniel Paxson, an accredited scientist at the Glenn Research Center, has used simulations in computational fluid dynamics (CFD) to assess the RDE's detonation frame of reference and compares the performance with the PDE.[12] He found that the results from his code of the RDE were shown to be in favor of those from a more complex code; thus, stating that the RDE can perform at least on the same level. Furthermore, he found that the performance of the RDE can be directly compared to the PDE as their performance were essentially the same.

Other experiments conducted used numerical procedures to comprehend the flow-field of the RDE. Douglas Schwer, another accredited author, used algorithms he used in a previous experiment involving PDE to evaluate the performance of the RDE. He found both engine essentially perform the same, but there are slight differences in variable pressures.[13] He concluded that the performance of this engine is dependent on "the pressure ratio between the micro-nozzles stagnation pressure and back pressure."[13]

References

  1. ↑ Lu, Frank; Braun, Eric (7 July 2014). "Rotating Detonation Wave Propulsion: Experimental Challenges, Modeling, and Engine Concepts". Journal of Propulsion and Power. The American Institute of Aeronautics and Astronautics. 30 (5): 1125–1142. doi:10.2514/1.B34802.
  2. ↑ "US Warships Could Soon Run on Detonated Waves". Gizmodo. Retrieved 2015-11-09.
  3. ↑ "Google Patents". patents.google.com. Retrieved 2015-10-21.
  4. ↑ "Shmuel Eidelman, Inventor, Rockville, MD". www.patentbuddy.com. Retrieved 2015-10-21.
  5. ↑ "How the Rotating Detonation Engine Works". HowStuffWorks. Retrieved 2015-10-21.
  6. ↑ "Green Car Congress: Navy researchers project Rotating Detonation-Wave Engines could yield 10% power gain, 25% reduction in fuel burn over gas turbines". www.greencarcongress.com. Retrieved 2015-11-09.
  7. ↑ "How the Rotating Detonation Engine Works". HowStuffWorks. Retrieved 2015-11-09.
  8. ↑ Today, Physics (2012-11-06). "US Navy developing rotating detonation engine". Physics Today. ISSN 0031-9228.
  9. ↑ "How the Rotating Detonation Engine Works". HowStuffWorks. Retrieved 2015-10-21.
  10. ↑ "Navy Researchers Look to Rotating Detonation Engines to Power the Future - U.S. Naval Research Laboratory". www.nrl.navy.mil. Retrieved 2015-11-09.
  11. ↑ "How the Rotating Detonation Engine Works". HowStuffWorks. Retrieved 2015-11-09.
  12. ↑ "UCSB Full Bib - External Link". pegasus.library.ucsb.edu. Retrieved 2015-11-09.
  13. 1 2 Schwer, Douglas; Kailasanath, Kailas (2011-01-01). "Numerical investigation of the physics of rotating-detonation-engines". Proceedings of the Combustion Institute. 33 (2): 2195–2202. doi:10.1016/j.proci.2010.07.050.

External links

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