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combustion doesn't occur need help plz

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Old   December 22, 2011, 09:55
Default combustion doesn't occur need help plz
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Boudour
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i am working on 2D combustion chamber i achieved the cold flow and now i am working on combustion i used eddy dissipation model to model combustion but the rate reaction still 0 even with mass fraction of co2 and h2o =0
i use k epsilon for turblent model and group injection for diesel C10h22
my conditions boundary are pressure inlet -oulet
please does anyone have an idea why the combustion doesn't occur with eddy dissipation model
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Old   December 26, 2011, 15:38
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Mosi Owa
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What is your initial temperature? Do you initialize your domain with a high temperature or not?
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Old   December 26, 2011, 21:01
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try to run the simulation for various higher temperatures.
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Old   December 27, 2011, 10:28
Default re: cpmbustion doesn't occur
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first of all thank you for replying
i initialize my temperature to 300 k but the temperature in the combustion chamber is about 900 k isn't enough for the combustion of diesel
i even try the patch but nothing that happens
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Old   December 27, 2011, 10:33
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thank's for replying
my initial temperature is about 300 k
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Old   December 27, 2011, 12:01
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No combustion reaction occurs at 300
use higher temp as around 600- 1000 and see the various products
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Old   December 27, 2011, 15:57
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Quote:
Originally Posted by shk12345 View Post
No combustion reaction occurs at 300
use higher temp as around 600- 1000 and see the various products
I agree too; use 1000 k and let us know what happens.
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Old   December 28, 2011, 04:13
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this is the details of my case

•Select k-epsilon model (realizable) under Viscous Model
•Under Species & Transportation I select "Species Transport", Mixture properties "diesel-air" with everything else unchanged.
volumetric : eddy dissipation model
•Now I set up DPM. Enable "interaction with continous phase", enable "unsteady particle tracking", Number of Continous Phase Iterations per DPM Iteration set to 200.
?under Physical Models i enable "DRoplet Collision" and "Droplet Breakup Model". Under Break up constant I set "Breakup Parcel to 50".
?Under Tracking Tab I set Drag Law to "dynamic-drag"
?Particle time step set to 0.00001


•Injections: I create an injection. "group". Particle Type "Droplet". Material "Diesel Liquid". Flow Rate to be 3.22e-4 kg/s. crank angle 700, Stop Time 720.temperature diesel 310k
?Under Turbulent Dispersion I enable "Discrete Random Walk Model" and "Random Eddy Life"
•Under Solve-> Controls -> Solution I leave default settings and select OK
•Now I select Initialize.to 1600k.

when the iteration finished i go to track particle :and i have this summary

Fate Number Elapsed Time (s) Injection, Index
Min Max Avg Std Dev Min Max
---- ------ ---------- ---------- ---------- ---------- -------------------- --------------------
Evaporated 831 3.989e-02 4.000e-02 3.995e-02 0.000e+00 injection-0 0 injection-0 0

(*)- Mass Transfer Summary -(*)

Fate Mass (kg)
Initial Final Change
---- ---------- ---------- ----------
Evaporated 3.434e-08 0.000e+00 -3.434e-08

(*)- Energy Transfer Summary -(*)

Fate Energy (J) Change of Energy (J)
Initial Final Sensible Latent Total
---- ---------- ---------- ---------- ---------- ----------
Evaporated -9.046e-03 0.000e+00 -1.468e-03 1.051e-02 9.046e-03


number tracked = 7297, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 7297, coalesced = 0, shed = 0, splashed = 0
one thing that i don't understand is why the evaporated ones are 0 and the incompleted ones are 7297
still nothing happen
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Old   December 28, 2011, 15:01
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check the arhenius parameters from literature
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Old   December 29, 2011, 04:06
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thank you for replying
eddy dissipation model doesn't take in account the arhenus chemical reaction are you talking about finte rate / eddy disspiation model ?
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