# equivalence ratio calculation on star-cd cell

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 April 10, 2012, 06:32 equivalence ratio calculation on star-cd cell #1 Member   Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 10 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, 21:52 #2 Member   zheng jianjun Join Date: Jan 2010 Posts: 46 Rep Power: 13 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 likes this.

 April 11, 2012, 02:04 #3 Member   Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 10 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 03:38.

 April 11, 2012, 04:43 #4 Member   zheng jianjun Join Date: Jan 2010 Posts: 46 Rep Power: 13 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 05:06.

 April 11, 2012, 06:34 #5 Member   Krishna Join Date: Apr 2012 Posts: 54 Rep Power: 10 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 ...