Flame speed at high Temperature/Pressure values

[John D]

Hi everybody

I was trying to use flamespeed example from

https://cantera.org/examples/python/onedim/flamespeed_sensitivity.py.html

but set To = 2000 and Po = 7 atm & Phi = 1 ... but when the problem is solved I get

mixture-averaged flamespeed = 3586506.412371 m/s

I can run the same case at T = 1500K and T = 1800 K and get flames speeds of approx

94 m/s and 4360 m/s, respectively.

Any idea why the flame-speed at 2000K is so high?  The flame speed at 1800K is also high (about Mach 5) but can imply strong detonation given the initial conditions.

Thanks

John

[Ingmar Schoegl]

At those temperatures you are seeing an autoignition process, which is by its nature very different from flame propagation. As the physics change, you cannot use those flame speeds as they are pure numerical artifacts. Hope this helps,

-is-

[John D]

Thanks, Ingmar.  I figured it was some numerical artifact.  I just wanted to confirm it.