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U.S. Navy investigates use of fuel-saving Rotating Detonation Engines

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November 4, 2012

Retrofitting engines on existing Navy ships, like the USS Arleigh Burke pictured here, wit...

Retrofitting engines on existing Navy ships, like the USS Arleigh Burke pictured here, with RDE technology could improve fuel efficiency (Image: U.S. Navy/Mass Communication Specialist 1st Class Tommy Lamkin)

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With around 430 gas-turbine engines on 129 of its ships burning about US$2 billion worth of fuel every year, the U.S. Navy is examining the potential of using Rotating Detonation Engines (RDEs) to improve fuel consumption and cut costs. Researchers at the Naval Research Laboratory (NRL) estimate that retrofitting RDEs to its fleet could save the Navy approximately 300 to 400 million dollars a year.

The U.S Navy currently relies heavily on gas-turbine engines because they are self-contained, relatively easy to maintain, and relatively small, yet scalable to large powers. They are used to provide propulsion and generate electricity for many of its ships and, being fundamentally similar to the engines used in commercial airplanes, they are also used in many Navy aircraft.

Even with the move towards “all-electric” propulsion systems for future ships, the NRL says gas-turbine engines will still be needed to generate electricity for the ships’ propulsion system and other critical systems.

The gas-turbine engines currently used by the Navy are based on the Brayton thermodynamic cycle, in which air is compressed and mixed with fuel and then combusted at a constant pressure. The resulting high velocity and volume gas flow is then directed through a nozzle over the turbine’s blades, spinning the turbine.

The NRL says that alternatives to the Brayton cycle need to be explored to improve the performance of gas-turbine engines. For the past decade it has contributed to the development of Pulse Detonation Engines (PDEs), which use pulsed detonation waves to combust the fuel and oxidizer mixture, but believes RDEs may offer the potential for even greater fuel efficiency.

A model of a Rotating Detonation Engine constructed by NRL researchers (Image: U.S. Naval ...

RDEs are similar to PDEs, but produce axial thrust by using a detonation wave that continuously travels around to detonate the incoming propellants. The RDE would offer improved efficiency over PDEs because the combustion chamber doesn’t need to be purged between detonations (pulses), as is the case with PDEs.

Building on earlier work done on general detonations, the NRL researchers have constructed a model for simulating RDEs and will now focus on gaining a better understanding of how they work and what type of performance can be achieved in the real world. They believe RDEs could be a disruptive technology in ships and planes, potentially providing the ability to meet a 10 percent increase in power requirements while reducing fuel use in future Navy applications by 25 percent.

Source: NRL

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
7 Comments

The ship should have been nuclear powered with reactors that came off a real assembly line.

Pikeman
4th November, 2012 @ 07:23 pm PST

If there is no purging, there will be some mixing, of old and new gases. if this is offset with high flow, there will be higher fuel consumption, overall efficiency will decrease, also

because some isolation of parts of the cycle are required to build actual pressure, which can't be offset by high flow. Which reverses the goal.

Solution is the hybrid system. High density batteries charged both when ship is off mission which is most of the time by solar power, plus the new multi combined cycle engine for generating electricity and charging batteries when on mission. The engine reported in gizmag recently.

Dawar Saify
5th November, 2012 @ 05:30 am PST

I don't pretend to understand the physics, but I hope this technology would be applicable to gas turbines that generate power in the private sector also.

Bruce H. Anderson
5th November, 2012 @ 08:18 am PST

Sounds like a good idea. There is no need for purging because some cross contamination will not hurt, because this is external combustion instead of internal combustion, with plenty of excess air. However, the high velocity flow, combined with the circular motion, should prevent any significant contamination. I also have to wonder if the direction of combustion rotation being the same as the turbine rotation will also help?

Rigby5
5th November, 2012 @ 10:34 am PST

Agree with Pikeman, Nuke is cheaper with the current 20 year fuel life/ 50 year reactor life. Diesel roughly doubled in price since 1987 to 2005, and a third again from 2005 (80p Litre)to 2011(140p Litre). Luckly goverments buy retail but still !.

L1ma
5th November, 2012 @ 10:45 am PST

Pikeman, explain your comments so that they make SOME sense.

NK Fro
5th November, 2012 @ 12:36 pm PST

Figuring over the forty-year life of the vessel --incl. building, maintaining, operating, decommissioning-- a nuclear powered ship actually turns out to cost almost twice as much. Here:

http://www.gpo.gov/fdsys/pkg/GAOREPORTS-NSIAD-98-1/html/GAOREPORTS-NSIAD-98-1.htm

Big navy ships are obsolete anyway. Here:

http://www.wired.com/dangerroom/2011/06/are-aircraft-carriers-slowly-becoming-obsolete/

Marco McClean
5th November, 2012 @ 04:22 pm PST
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