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-   -   equivalence ratio calculation on star-cd cell (http://www.cfd-online.com/Forums/star-cd/99710-equivalence-ratio-calculation-star-cd-cell.html)

kri321shna April 10, 2012 05:32

equivalence ratio calculation on star-cd cell
 
Hello,

Can you please help me in equivalence ratio calculation over computational domain. the fuel is -> C8H18.

my main problem is how to calculate the c8h18 for each cell over domain.:o

Thanks in advance.

regards,
Krishna

skylent April 10, 2012 20:52

please try this macro, bless.

*set,safr, 15.03442884 !stoichiometry air fuel ratio of iC8H18-kg/kg
operate,getc,conc,1,1 !the mass fraction of fuel vapor

operate,getc,conc,2,2 !the mass fraction of oxygen--
!
operate,smultiply,4.291845494,2,3
!the mass fraction of air in the cell=m_O2/0.233

operate,divide,1,3,5 !F/A =fuel air ratio
operate,smultiply,safr,5,4 !phi=F/A*sto_A/F
spoint 0 0 0
snormal 0 1 0 !
poption,contour !
pltype,section !
angle 0 !
view snormal !
cplot

kri321shna April 11, 2012 01:04

Thank you very much..

Can you please explain the below points:

1. why u are multiplying oxygen with 4.291845494.


this is how cell data stored
{ CELL DATA
SU "Velocity Component U" m/s
SV "Velocity Component V" m/s
SW "Velocity Component W" m/s
MassFlux "Mass Flux" kg/s
P "Pressure" Pa
PTER "Thermo. Pressure" Pa
TE "Turb Kinetic Energy" m2/s2
ED "Dissipation Rate" m2/s3
VIS "Turbulent Viscosity" Pa s
T "Temperature" K
H "Enthalpy" J/kg
DENS "Density" kg/m3
CP_M "Mean Specific Heat" J/kgK
CP "Specific Heat" J/kgK
COND "Conductivity" W/mK
CONC_001 "C8H18"
CONC_002 "N2"
CONC_003 "O2"
CONC_004 "WFMASS"
CONC_005 "WFTHICK"
CONC_006 "WFTEMP"
CONC_007 "RG"
VOID "Void Fraction"
}

2. please check the above commands once. operate,getc,conc,2,2 !the mass fraction of oxygen-- now i have to run it as a operate,getc,conc,2,3 !the mass fraction of oxygen--

can you please conform this.



Thanks in advance.:)

skylent April 11, 2012 03:43

Q1. why u are multiplying oxygen with 4.291845494.
answer: 4.291845494=1/0.233, multiplying oxygen with this value, you can get the mass fraction of air.


Q2. please check the above commands once. operate,getc,conc,2,2 !the mass fraction of oxygen-- now i have to run it as a operate,getc,conc,2,3 !the mass fraction of oxygen--

Answer: It is all right that you made a small modification as "operatre,getc,conc,2,3",due to the last number stands for "species number", and second to last number represents "register number".
---------------------------------------------------------------------------------------------------------------------------------------------------
operate GETC CONC,IREGS,NSC(1) ==Loads the mass fractions of scalar species NSC into register IREGS.

CONC_001 "C8H18"
CONC_002 "N2"
CONC_003 "O2"

kri321shna April 11, 2012 05:34

thank you so much ...
i have checked the operate command like..
operate,getc,conc,2,3

here 2 is the register and 3 is the conc value.


Thank you ...:):):):):):):):)


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