using FDS to simulate flare burning,thanks a lot!

[aqsxs]

to those who may concern it:

I  want to know whether FDS can simulate flare buring in process plants.because the gas is with high velocity in accidental emitting ,it march number is about 0.2~0.5.I know that FDS can export ideal result when March number is not larger than 0.3.So I must know whehter FDS can simulater gas buring with not so large movement speed?

If it can ,so,would you please send me the FDS example file,indiacting how to define the flare buring in *.fds file?

Thank you very much and look forward to your reply.

Best wishes

Eric.Song

P.S: Eric is a state certified safety assessment engineer who is mainly undertaking safety analysis for onshore and offshore modules with computation fluid dynamic technology.and he sincerely appreciate your support from FDS forum group.

 

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[S.Desanghere]

It is difficult to give you a precise answer without having more
information about what you are looking at: radiation from flares ?
Flare impingement ? Flare shape according to several parameters such
as discharge rate ?
I'm not sure FDS combustion model is able to correctly predict
chemical reactions at so high speed (Mach 0.5 is about 170 m/s), when
flame extinction due to high shear stresses can occur for example.
It seems tricky, but maybe you can adapt the fire source from the
"spray burner" example given in FDS documentation to model the case.

[Kevin]

Whether FDS can or cannot simulate a certain physical phenomenon is a
judgment that you, the end user, must make. There is no exact value of
the flow speed at which the low Mach number assumption no longer
applies, for example. If you are new to FDS, I suggest you start with
a simpler case. As S. Desanghere says, there are cetain phyical
mechanisms, like flame extinction and/or blow-off at high strain rate,
that are not modeled using the default combustion model. You should
become familiar with the model and its various different modes of
operation before applying it to your case.

[eric.song]

Thank you Desanghere for your quick and heuristic response.

I am trying to simulate the flame shape and its radiation strength to
the ground.According to relevant state standards,the gas speed runing
out of the outlet of the flare is in the range of 0.2-0.5 March
numbers.I think that FDS is very good at simulating the combustion
process and radiation effect as buring on a solid surface or pyrolysis
of the soild or liquid fuel.But I dont find the appropriate method to
simulate the jet fire,that is the fuel(gas)is buring as it is moving
with fast speed.
I do not need to simulate flame impingment.
So would you please give me some other suggestions with regards to
flame shape ,combustion radiation of the flare buring with the fuel
CH4.The burning process is that ,the CH4 is buring above the flare
outlet and the new gas is running out to burn.
Another is would you please send me some handbook,pdf version is
good,that can provide some heat parameters such as heat release
rate,combustion energy ,ect.
Thank you very much!
Eric.Song

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[dr_jfloyd]

please do not request that group members send pdf versions of
copyrighted material.

[S.Desanghere]

Eric,

Well, to me your latest question is very general and somewhat
irrelevant in a discussion forum focused on FDS.

I'm not specialist in flare radiation but after simply having typed
"radiation from flares" in google, here are the first two references I
found (I precise I don't know their relevancy !) :
http://environment.gov.ab.ca/info/library/6694.pdf
http://www.johnzink.com/products/flares/pdfs/tp_radiation.pdf
etc. etc. etc.

Fortunately, there is a lot of free material on the web to start a
bibliographical study.
Of course we're not going to share copyrighted material.

I wish you a good research !