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-   -   combustion (http://www.cfd-online.com/Forums/fluent/44319-combustion.html)

zenith April 2, 2007 05:40

combustion
 
i am using pdf model with equilibrium, non adiabetic options. according to theoritical calculation

1) Adiabetic flame temperature of kerosene should be 2300 kelvin, but i am having max temp. upto 2550 kelvin in my solution domain. What could be the reason

2) Heat added by the fuel comes far less than the theoritical value. so the outlet temperature is coming on the lower side for the oxidation of same amount of fuel. I assume all the paritcale evaporate should produce heat.

i have activated 5 species. including co and co2.

Including more species in calculation can make effect on heat released by the fuel and max temp?

thanxs in advance

zenith mark

Phil April 8, 2007 21:07

Re: combustion
 
these cfd models generally aren't that accurate. you need a detailed reaction mechanism. There could though be a million reasons for the high temp. Look for papers with similar calculations.

you should try species transport with volumetric reactions perhaps eddy dissipation and see what the temp is.

also try a lower air temp and check your other calcs. This is the way it is, bang your head off a brick wall for hours,days,weeks,months one of those then at a random time it clicks into place.

good luck.

zenith April 10, 2007 13:27

Re: combustion
 
Thanks Dear

i am using air entering at temperature 700K. If i lower the entering temperature of air, then i think adiabetic temperature will not be exceed.

Can u let me know about any source from where i can get the mechanism reactions for kerosene.

thanks in advance

zenith

Phil April 10, 2007 14:22

Re: combustion
 
not sure - would need to speak to a University or search online.

zenith April 10, 2007 14:59

Re: combustion
 
Hi

Phil do you have any idea, what does this message means

" particle concurrency 5% "

while modelling injection in dpm model

zenith

jeffery April 12, 2007 15:52

Re: combustion
 
There is an assumptiom in the procedure of calculating adiabetic temperature that both fuel and air are room temperature is applied . So, it is possible the combustion temperature is higher than adabetic temperature if inlet air temperature is very high. BTW, Cp value for air and combustion products is a function of temperature. You should define it yourself. Else you will get higher temperature.

mohamed saleh May 1, 2007 09:13

Re: combustion
 
i'm pleased to know you,please help me to find the following: all files is required: data base,mesh,case,data and analysis file

mohamed saleh May 1, 2007 09:17

Re: combustion
 
i'm pleased to know you,please help me to find the following: all files is required: data base,mesh,case,data and analysis file

Phil May 1, 2007 10:26

Re: combustion
 
I am unsure what you mean by 'find' the files.

database = .dbs mesh = .msh case = .cas data = .dat analysis = ?(unsure)

these are the file extensions that Fluent uses. You need to create these files yourself using Gambit then Fluent. This is what CFD is!

You can find tutorial files with all these extensions.


mohsen May 16, 2007 09:22

Re: combustion
 
about swirl burner


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