Supersonic Combustion

  • Thread starter Clausius2
  • Start date
  • #1
Clausius2
Science Advisor
Gold Member
1,435
5

Main Question or Discussion Point

Ok. Let's suppose the next imaginary experiment. I encouragely promise that I don't know anything about nowadays supersonic combustion problems. I want to continue with the discussion spread in the "rocket thrust" thread, and what Enigma and Russ Waters said.
There is a supersonic flow at the entrance of combustion chamber, due to the intake of air. Why it does not possible generate a combustion steady wave (i.e. a detonation wave) in the combustion chamber. A weak detonation causes a supersonic flow behind it. I heard the Chapman-Jouguet detonations are possible oftenly.
How could I generate a steady detonation?, I mean a detonation that no moves in the laboratory reference axes.
I have another idea: what about heating the supersonic inlet current?.
The Mach number will decrease, but would it descent below M=1?. In this case would occur a shock wave at the intake?.
 

Answers and Replies

  • #2
LURCH
Science Advisor
2,549
118
I think one of the problems with continuous detonation is how to intake air into the fire. As you've pointed out, a detonation creates a supersonic shockwave which spreads outward in every direction away from the center. If the shockwave were stationary relative to the laboratory frame of reference, how would air get in?
 
  • #3
Clausius2
Science Advisor
Gold Member
1,435
5
I was not thinking of an spherical shock wave. It would be a part of an sphere, or a plane wave indeed.
I claim to the combustion expertises to try to get rid of my theory giving a powerful reason of why it is not possible (nowadays).
 
  • #4
LURCH
Science Advisor
2,549
118
But I think it is the nature of any detonation to propagate outward in all directions equally. I can think of no way to make a partially spherical wave or planewave out of the shockwave from a detonation, other than blocking one side with a barrier, which would also prevent the inflow of fuel.

Do you know of a way to generate a blast of that shape so that fuel flow will be permitted? I keep trying to imagine one, but I keep running into dead-ends.
 
  • #5
Clausius2
Science Advisor
Gold Member
1,435
5
I was thinking like in a burner in which fuel flow and breathing air are mixed coaxially and axilsimmetrically, with the fuel inflow at the centre. It would be a diffusion flame, but now, Is it possible a detonation in such a burner, if the air intake is supersonic?. Would there be enough residence time for burning?. If that is possible, there would be a detonation-steady wave in the laboratory frame, with a flame shape (with a continuous fuel intake).
But the scientists are not dull at all, so I'm waiting an answer telling me this idea is something like a cock and bull story.
 
  • #6
1
0
Dear all!
I have a problem in simulating the 1 dimensional znd structure for detonation. I want to use 1 step Arrhenius model for reactio. has any one done it before? please help me.
Thanks
 

Related Threads on Supersonic Combustion

  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
1
Views
701
  • Last Post
Replies
6
Views
947
  • Last Post
Replies
8
Views
6K
  • Last Post
Replies
8
Views
1K
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
22
Views
4K
  • Last Post
Replies
13
Views
3K
  • Last Post
Replies
8
Views
11K
  • Last Post
Replies
4
Views
9K
Top