equivalence ratio calculation on star-cd cell

kri321shna · April 10, 2012, 05:32

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.

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 ...

April 10, 2012, 05:32	equivalence ratio calculation on star-cd cell	#1
kri321shna Member Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 14	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. Thanks in advance. regards, Krishna

April 10, 2012, 20:52		#2
skylent Member zheng jianjun Join Date: Jan 2010 Posts: 46 Rep Power: 16	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/Asto_A/F spoint 0 0 0 snormal 0 1 0 ! poption,contour ! pltype,section ! angle 0 ! view snormal ! cplot kri321shna likes this.

April 11, 2012, 01:04		#3
kri321shna Member Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 14	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. Last edited by kri321shna; April 11, 2012 at 02:38.

April 11, 2012, 03:43		#4
skylent Member zheng jianjun Join Date: Jan 2010 Posts: 46 Rep Power: 16	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 likes this. Last edited by skylent; April 11, 2012 at 04:06.

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April 11, 2012, 05:34		#5
kri321shna Member Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 14	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 ...