Visualizing flame front by temperature isosurface in abnormal combustion

HariHari · November 15, 2018, 06:22

Hi,
I want to visualize the flame propagation by temperature isosurface (simulating abnormal combustion), but not getting how to select the temperature. I have gone through the AdvICE-EngineKnock ppt’s of CONVERGE in which it is mentioned that “Use a temperature isosurface of 1700 K to represent the main flame”.
I have a query that why 1700 K? Is it a standard way to represent flame? What is the reference for this? Does this value depend on the type of fuel?

SamWijey · November 15, 2018, 10:37

Hello,

The use of 1700 K is just a choice. The turbulent "flame" is not an infinitesimally thin one, but has some thickness to it. Temperature changes from the unburnt to (nearly) adiabatic flame temperature across the flame. Hence you cannot pick one temperature and say that's the best choice for the flame. But any choice of temperature between the unburnt and adiabatic flame temperature are representations of the flame.

Intermediate species OH is being produced on the flame and O2 is depleted on the flame. You can combine several of these parameters to come up with your own definition of the flame.

In simplified combustion models, when they show you 'where the flame is', that is also based on a particular definition to represent what the flame is.

Hope this helps,

HariHari · November 16, 2018, 02:37

Great...

Thank you very much Sameera for the reply

November 15, 2018, 06:22	Visualizing flame front by temperature isosurface in abnormal combustion	#1
HariHari New Member Vipin Join Date: Oct 2016 Location: New Delhi Posts: 4 Rep Power: 10	Hi, I want to visualize the flame propagation by temperature isosurface (simulating abnormal combustion), but not getting how to select the temperature. I have gone through the AdvICE-EngineKnock ppt’s of CONVERGE in which it is mentioned that “Use a temperature isosurface of 1700 K to represent the main flame”. I have a query that why 1700 K? Is it a standard way to represent flame? What is the reference for this? Does this value depend on the type of fuel? KapilO8 likes this.

November 15, 2018, 10:37		#2
SamWijey Senior Member Sameera Wijeyakulasuriya Join Date: Jan 2016 Location: Convergent Science, Madison WI Posts: 118 Rep Power: 10	Hello, The use of 1700 K is just a choice. The turbulent "flame" is not an infinitesimally thin one, but has some thickness to it. Temperature changes from the unburnt to (nearly) adiabatic flame temperature across the flame. Hence you cannot pick one temperature and say that's the best choice for the flame. But any choice of temperature between the unburnt and adiabatic flame temperature are representations of the flame. Intermediate species OH is being produced on the flame and O2 is depleted on the flame. You can combine several of these parameters to come up with your own definition of the flame. In simplified combustion models, when they show you 'where the flame is', that is also based on a particular definition to represent what the flame is. Hope this helps, arvindpj, EDE16 and KapilO8 like this. __________________ Sameera Wijeyakulasuriya Principal Engineer, Applications CONVERGECFD

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November 16, 2018, 02:37		#3
HariHari New Member Vipin Join Date: Oct 2016 Location: New Delhi Posts: 4 Rep Power: 10	Great... Thank you very much Sameera for the reply