What Are the Advantages of a Rotating Detonation Engine for Naval Ships?

In summary, the 2016 paper by Bulat and Volkov and the 2013 paper by Nordeen et. al. discuss the thermodynamic efficiency of rotating detonation engines (RDEs) compared to traditional jet engines. The papers show that at Mach 2, the ideal specific impulse for H2-air mixtures is 8500s for an FJ detonation cycle, while the simulated impulse is only 60% of ideal. The first paper also shows the thermodynamic conversion coefficient, which is assumed to be efficiency, for both an FJ cycle and a Brayton cycle. It is concluded that at compression ratios above 10, a traditional jet engine would be more efficient than an RDE. However, for
  • #1
yangshi
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Just trying to understand how efficient RDE's are thermodynamically based on a 2016 paper from Bulat and Volkov titled "Detonation Jet Engine. Part 1 – Thermodynamic Cycle" and a 2013 paper by Nordeen et. al. titled "Thermodynamic Model of a Rotating Detonation Engine":

Based on these papers, at Mach 2 (just before the detonation front?), ideal specific impulse for H2-air mixtures is 8500s (FJ detonation cycle) while simulated impulse is ~5000s or 60% of ideal. Fig. 4 of the first paper shows thermodynamic conversion coefficient (assuming this is efficiency) vs. compression ratio b/w an FJ and Brayton cycle.

Assuming that specific impulse is proportional to efficiency and that jet engine efficiency is 90% of that of the ideal Brayton cycle (turbofan), one could conclude that at CR>10-ish, an actual jet engine would have higher thermodynamic efficiency than an actual RDE. For all other scenarios (engines with low compression ratios or that sacrifice efficiency for speed), an RDE can be more efficient?

Also, from http://physicstoday.scitation.org/do/10.1063/PT.5.026505/full/, why would the Navy want to replace their ship engines (assuming diesel engines) with RDEs since RDEs have efficiency loss from the strong detonation shock wave while diesel engines only have efficiency loss from a weaker deflagration wave? Is the FJ detonation cycle just more efficient overall than the diesel cycle?

I asked my combustion advisor this, and he was confused too. Any explanation would be appreciated. Happy holidays!
 
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  • #2
yangshi said:
why would the Navy want to replace their ship engines (assuming diesel engines) with RDEs since RDEs have efficiency loss from the strong detonation shock wave while diesel engines only have efficiency loss from a weaker deflagration wave?
Ships now use gas turbines for propulsive power. This will increase as electrical generators, motors and controls become more common.

If you consider that efficiency is a function of compression ratio, then the detonation provides an effective higher compression ratio. I believe the RDE is a more efficient gas generator and that it can replace the combustor(s) in a gas turbine engine.
 
  • #3
If the Navy is interested, it must because of claimed advantages. I recommend that you check the referrences of the following article for more details about the claims.
https://en.wikipedia.org/wiki/Rotating_detonation_engine
 

1. What is a rotating detonation engine?

A rotating detonation engine is a type of propulsion system that uses a continuous detonation wave instead of a traditional deflagration combustion process. It involves a self-sustaining detonation wave rotating around the circumference of the engine, providing a more efficient and powerful thrust.

2. How does a rotating detonation engine work?

A rotating detonation engine works by igniting a fuel-air mixture in a continuous detonation wave in a ring-shaped channel. This detonation wave rotates around the circumference of the engine, constantly compressing and igniting the fuel mixture, leading to a continuous and sustained thrust.

3. What are the advantages of a rotating detonation engine?

A rotating detonation engine offers several advantages over traditional engines, including higher efficiency, greater power output, and potential for using a wider range of fuels. It also has a smaller size and weight compared to other engines, making it ideal for use in aerospace and other applications.

4. What are the challenges of developing a rotating detonation engine?

Developing a rotating detonation engine is a complex and challenging process, with several technical hurdles to overcome. These include controlling the detonation wave, managing the extreme temperatures and pressures involved, and ensuring the engine's stability and reliability over long periods of operation.

5. What are the potential applications of a rotating detonation engine?

A rotating detonation engine has the potential to revolutionize propulsion technology and could be used in various applications, including aircraft, rockets, and even power generation. It could also be adapted for use in other industries, such as transportation and manufacturing, where high-powered and efficient engines are required.

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