Pulse Detonation Engine Technology

Pulse Detonation Engine

Pulse Detonation Engine is a propulsion technology. Involves detonation of fuel to produce thrust. More efficient than current engine system. Basic concept behind the technology is to detonate, rather than deflate,the fuel. The detonation of fuel results in immense pressure which in turn is used as thrust. Supersonic velocities can be achieved. The basic operation of the Pulse Detonation Engine is similar to that of the pulse jet engine. In the pulse jet, air is mixed with fuel to create a flammable mixture that is then ignited in an open chamber. The resulting combustion greatly increases the pressure of the mixture to approximately 100 atmospheres. The first known flight of an aircraft powered by a pulse detonation engine took place at the Mojave Air & Space Port on January 31, 2008. 

Why Pulse Detonation Engine?

Why Pulse Detonation Engine? Answer to the question is limited in following points:

    • Simplicity of design.
    • Detonation wave does the work of compressing the gas, producing extremely high pressure ratios, higher temperatures.
    • No requirement of high compression ratios and thus no compressor required.
    • Constant volume combustion offers better efficiencies than constant pressure combustion in Brayton cycle.
    • Better thrust, Isp, fuel efficiencies.
    • Higher weight to thrust ratios.

Pulse Detonation Engine

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Pulse Detonation Engine Working Principle

Working Principle of Pulse Detonation Engine is Two stage ignition process

In first stage

  • Injection of fresh air – fuel charge.
  • A volatile fuel (h2)  and  oxidizer (o2) injection.
  • powerful electrical discharge ignition.
  • DDT Tubes are used for triggering.

In Second Stage

  • Powerful shock wave generation.
  • Main AIR+ FUEL Charge compression.
  • Repetition of both stages.

Fuel Options for Pulse Detonation Engine

There were many options for fuel some of which are depicted here

  • Coal: Efforts are under way to produce clean coal gas
  • Natural gas: LPG, CNG etc
  • Propane
  • Hydrogen
  • Kerosene
  • Jet fuels
  • Octane

Advantages of Pulse Detonation Engine

Some of the major advantages of Pulse Detonation Engine or Pulse Jet Engine are given here

  • The inherent mechanical design simplicity.
  • Easy integration and maintenance.
  • Higher thermodynamic efficiency.
  • Higher mach number up to 5 can be achieved.
  • Much better fuel efficiency.
  • No need of compressors and turbines.
  • Theoretically lesser weight as compared to conventional gas turbine engine.
  • Cost effective.
  • NOx emissions may decrease up to 70 – 80 %.

Limitation of Pulse Detonation Engine

  • Attaining successive detonation instead of deflagration cycles.
  • The risks of containment failure (i.e. catastrophic explosion that turns engine into a grenade).
  • Problems in valve operation.
  • High vibration and noise levels.
  • Engineering materials to withstand the immense pressure and thermal stresses caused by the detonation.

Applications of Pulse Detonation Engine

  • In – atmosphere flight.
  • Quick and efficient inter continental travel.
  • Application to space flights.
  • Safe and cost effective space craft launch.
  • Effective military operation.

Future Projects of Pulse Detonation Engine

  • Many developers have a high hopes that PDE will ultimately become the most cost effective method of propelling supersonic sub – orbital craft.
  • The ultra – high compression obtained by detonation offer the potential for much better fuel efficiency than even the best turbojet.
  • An air breathing engine reduces the fuel load and increases safety when compared to rocket motors.

CONCLUSION

Pulse detonation engines can be classified into three categories Pure, Combined cycles and Hybrid. General principle of operation for each is identical.

The fuel-air mixture is detonated in the engine cavity , rather than deflagrate. It has an inherently simpler mechanical design and a higher thermodynamic efficiency. It is more efficient , in both specific thrust and specific fuel consumption. Pulse detonation engine technology has application to many aerospace industries,quick and efficient intercontinental  travel, safe and cost effective spacecraft launch and military operations.

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