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-   -   Combustion problem, Temp to high. (http://www.cfd-online.com/Forums/fluent/29890-combustion-problem-temp-high.html)

Devin June 11, 2002 14:39

Combustion problem, Temp to high.
 
Hello everyone,

I'm trying to model an HVOF thermal spray process, but I'm having some difficulty. I'm getting temperatures in excess of 4500K when the flame temperature of propylene is approx. 2300K.

The model is using ideal-gas as it is a supersonic flow and the standard k-e model for turbulence. The boundary condition for the fuel inlet is a propylene-oxygen mixture. I suspect this may be my proplem. I've done some other cases involving separate fuel and oxygen supplies with better results.

Any thoughts?

Devin

Erwin June 12, 2002 05:20

Re: Combustion problem, Temp to high.
 
Are you using a radiation model to get rid of some energy? That might help.

Jin-Wook LEE June 13, 2002 20:54

Re: Combustion problem, Temp to high.
 
Flame temperature of propylene 'WITH AIR ' may be approx. 2300K, but flame temperature 'WITH OXYGEN' might be higher than 4500K.

Sincerely, Jinwook


newbie June 14, 2002 02:29

Re: Combustion problem, Temp to high.
 
What will the flame temperature be for kerosene and how does one go about determining the value? If I am simulating a combustor, how do i know if the flame temperature is too high?

Jin-Wook LEE June 16, 2002 20:37

Re: Combustion problem, Temp to high.
 
Adiabatic flame temperature of most fuel with 'AIR' as oxidant is about 2000C(~2300K) or higher.

Theoretically, Adiabatic flame temperature of most fuel with OXYGEN as oxidant might be higher than 4000K. But this is only theoretical value. In general they say that, in real experiment, the flame temperature is lower than 4000K because of dissociation.

Calculation of Adiabatic Flame Temperature(AFT) :

Q_in = Integral from T_ref to T_aft dot M Sigma (Cp)_i dot m_i dT

Where,

dot M : total mass flow rate dot m : mass fraction of each species Cp_i : specific heat of each species ...... ......

Sincerely, Jinwook


Devin June 17, 2002 15:01

Re: Combustion problem, Temp to high.
 
Thanks, everyone, for your input. Greatly appreciated.

Devin

Mohammed Khan April 26, 2012 05:46

Quote:

Originally Posted by Devin
;101290
Hello everyone,

I'm trying to model an HVOF thermal spray process, but I'm having some difficulty. I'm getting temperatures in excess of 4500K when the flame temperature of propylene is approx. 2300K.

The model is using ideal-gas as it is a supersonic flow and the standard k-e model for turbulence. The boundary condition for the fuel inlet is a propylene-oxygen mixture. I suspect this may be my proplem. I've done some other cases involving separate fuel and oxygen supplies with better results.

Any thoughts?

Devin

Dear Devin,
I am modeling the HVOF process in fluent and I am also getting very high temperature. I hope u got the solution for that. Could u please tell me the solution for getting the temperature around 2500.
Thanks


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