The Audible Difference between Deflagration and Detonation

This video shows the audible difference between deflagration and detonation, the two main types of combustion. Here, a pulsed detonation engine is operated in deflagration mode (like a pulsejet) using a propane/air fuel mixture. Next, pure oxygen is used instead of air and detonation occurs. The detonation waves have a much more profound effect on the flag and metal plate. The resulting increase in thrust is approximately 200%. These PDE tests took place at the UT Arlington Aerodynamics Research Center in 2008.

Category:

Science & Technology

Tags:

• aviation
• pde
• space
• pulse
• detonation
• engine
• deflagration
• combustion

[tomterahedrob]

Thank you!5*.Please keep this posted!How much more efficient, more thrust do you get with detonation as opposed to the deflagration?Did the measure it here?

[emb8]

Here there was about a 200% increase in thrust between deflagration and detonation. More fuel was used for the detonation, so that increase does not translate directly to an efficiency comparison. I think the current consensus is a PDE should be 10-20% more efficient than a turbojet.

[afrolion44]

you say tomato I say potato 

[dtiydr]

Dam..

[gcr100]

you need to put a hs camera in there

[Mathview]

The acoustic wave Power Spectrum P(f) would be a quantitative representation of this phenomenon, with f the frequency. Easy enough to obtain with a wide band acoustic pickup and ADC. FFTs and power spectral analysis gets P(f). The detonation signal should have a flat or flatter P(f) signature, at least that's what it sounds like to me.

[marmaladekamikaze]

That's some nice info, thanks friend, always wondered about that, Do you mind if I ask where you read that?

[monimstarfox]

deflagration sounds like a 9mm

Detonation sounds like a .50

[displayfireworks1]

This is a great upload. You can hear why fireworks dont detonate as people believe.

[TheMarvelousMarw]

you can see the sonic barrier :=

[archileach]

The problem with an ICE utilizing denonation rather than deflagration, is that the product of detonation is a high pressure wave front. It's possible to make an engine that will withstand this by lowering the fuel content, but the available pressure after the wave front is too small to power the pistons as efficiently as that provided by deflagration.  You get an engine with high rpm but with low HP and Torque. What you really want is low rpm and high torque.

[tomterahedrob]

Thanks for the great info you just cant find in any book.