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Old   August 31, 2013, 08:51
Default CI simulation
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ali
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hi
I'm a novice user in AVL FIRE. i want to simulate the closed Cycle of CI Combustion. of course my compression ratio is 11 & for this reason i used high temprature in beginning of cycle (550 K in BDC). injection is done in 697 deg ,but i have a very weak ignition. for example my burnt fuel mass fraction is 0.000005 in 720 deg & maximum rate of heat release is 2 j/deg!!! as a another result i have a motoring pressure for my pressure diagram!! I checked any data, but i didnt have any success in my problem..
tnx for any help & proposal.

Last edited by yousefzadeh; August 31, 2013 at 12:33.
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Old   September 1, 2013, 21:17
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Myunghwan Kim
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Hi,

Even though your information is not enough, please check..
- initial cylinder pressure
- injected/evaporated/remaining fuel mass
- cylinder pressure/temperature trace during simulation

If Breakup/Evaporation are OK, you should check the combustion parameters.

After check, please show more information.
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Old   September 2, 2013, 02:12
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ali
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i checked all of this parameter that you said before, & they are not logical for self ignition.
but i got a great point that fractions of air components are not logical at all. in fla file & species mass fraction:
for example O2 mass fraction is about 1e-10 & N2 is about 0.7!! i think this is my problem, that i dont have any choises in fluid propertis for air..
combustion model is eddy beak up
my initial pressure is 256000 Pa.
tnx for any suggestion.
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Old   September 2, 2013, 21:30
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Myunghwan Kim
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looks strange.
I guess you defined EGR mass fraction in initial condition.
Please describe your inputs in "Standard species transport" of INITIAL CONDITIONS.
Did you also check spray evaporation?
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Old   September 3, 2013, 02:51
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ali
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yeah,your guess is true. i had a mistake that defined the EGR mass fraction in initial condition. after solving this problem i run my case & there are some results that obtained:

max Rate of Heat release: 29 j/deg
max burnt fuel mass fraction:0.008
max mass fuel evaporated: about 8e-5 kg
fuel mass: 0.00037 kg

i dont have a good fuel evaporation & i can't find this reason..
fuel is diesel & maximum temprature is 1100 K.

tnx...
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Old   December 15, 2013, 12:56
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mehdi
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hi guys!
im recently working by fame engin plus.any body knows in fame engin plus at input surface section what is the range of cranck angle(valid from... to... cranck angle)?
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