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subroutine reacfn.f

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Old   February 15, 2006, 21:39
Default subroutine reacfn.f
  #1
kris
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I am thinking of using star-subroutine reacfn.f

sample code included Hybrid-reaction model is as follow

************************************************** ******

SUBROUTINE REACFN(RATE)

~~~~~~~~~~~~ abbrev. ~~~~~~~~~~~

CC WMF and WMR are fuel and reactant molecular weights

ZERO=0.0

WMF=16.0

WMR=32.0

UGC=8314.3

IF(IR.EQ.1) THEN

CC Eddy break-up rate dependent on minimum of fuel, reactant and CC Product mass fractions

RMFR=MAX(ZERO,AMFU)

RRFR=MAX(ZERO,AMRC(1)/4.0)

RMFR=MIN(RMFR,RRFR)

RPFR=MAX(ZERO,BEBM*AMFB)

RMFR=MIN(RMFR,RPFR)

CC Eddy break-up reaction rate

RSOUE=DEN*TAUL*AEBM*RMFR

CC Chemical kinetic rate

RCON=ARCK*WMF*

* T**BETCK*EXP(-EACT/(UGC*T))

RCON=RCON*(DEN*MAX(ZERO,AMFU)/

* WMF)**RTCKF

RCON=RCON*(DEN*MAX(ZERO,AMRC(1))/

* WMR)**RTCKR(1)

CC Minimum rate

RATE=MIN(RSOUE,RCON)

ENDIF

************************************************** ******

2-step reaction model

1st C3H8 + 3.5O2 -> 3CO + 4H2O ==>rate1

2nd CO + 0.5O2 -> CO2 ==>rate2

if i want to use 2 step model, how do I use those? because the problem is that return value is only one "RATE"!

in addition, I compared with result using subroutine sample codes and using STAR-CD setting value about 1 step reaction model

but I found out different contours of Temperature

what is the problem?

thank you for my words

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Old   February 17, 2006, 14:20
Default Re: subroutine reacfn.f
  #2
Yongzhe Zhang
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Parameter IR indicates which reaction RATE corresponds to. So this subrotine is called for each reaction, each cell. You only need to do sth. like if (ir. eq. 1) ... rate=rate1 elseif (ir .eq. 2) ... rate=rate2 endif

You need to make sure you set up everything exactly same to each other for the two cases. THe sample subroutine apparently is a combined-rate EBU model. In pro-star, you can set is as EBU, combined-time, combtined-rate or finite-rate chemistry.

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Old   February 20, 2006, 21:17
Default Re: subroutine reacfn.f
  #3
kris
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Dear. Zhang

I have one more question

I have make codes for propane and air

would you tell me why there is the different results between coding and PROSTAR setting(combined rate model)

my coding have something wrong ?

the sample code is as follow 1-STEP(combined model)

************************************************** *

ZERO=0.0

WMF=44.1

WMR=32.0

UGC=8314.3

s_oxid=5*WMR/(1.0*WMF)

s_prod=1.0+s_oxid

Aebu=4.0

Bebu=0.5

IF(IR.EQ.1) THEN CC Eddy break-up rate dependent on minimum of fuel, reactant and

CC Product mass fractions

RMFR=MAX(ZERO,AMFU)

RRFR=MAX(ZERO,AMRC(1)/s_oxid)

RMFR=MIN(RMFR,RRFR)

RPFR=MAX(ZERO,Bebu*AMFB/s_prod)

RMFR=MIN(RMFR,RPFR)

CC Eddy break-up reaction rate

RSOUE=DEN*TAUL*Aebu*RMFR

cc Extinction

tau_tur=0.41*(VISM/DE/DEN)**(1/2)

tau_chem=DEN*AMFM/RSOUE

CC Minimum rate

IF(tau_tur<tau_chem) THEN

RSOUE=0.0

ENDIF

CC Chemical kinetic rate

RCON=ARCK*WMF*

* T**BETCK*EXP(-EACT/(UGC*T))

RCON=RCON*(DEN*MAX(ZERO,AMFU)/

* WMF)**RTCKF

RCON=RCON*(DEN*MAX(ZERO,AMRC(1))/

* WMR)**RTCKR(1)

RATE=MIN(RSOUE,RCON)

ENDIF ************************************************** ******

and more,...

when I make code as follow, Is the parameters in AMFB,AMFU in reaction1 part different with AMFB,AMFU in reaction2 ??

IF(IR.EQ.1) THEN ...

AMFB - Fuel burnt mass fraction

AMFU - Fuel mass fraction

AMRC(IA) - Reactant IA mass fraction

RTCKR(IA) - Reactant IA exponent

RATE=MIN(RSOUE,RCON)

ENDIF ...

IF(IR.EQ.2) THEN

...

AMFB - Fuel burnt mass fraction

AMFU - Fuel mass fraction

AMRC(IA) - Reactant IA mass fraction

RTCKR(IA) - Reactant IA exponent

RATE=MIN(RSOUE,RCON) ...

ENDIF

RETURN

END
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Old   February 23, 2006, 11:02
Default Re: subroutine reacfn.f
  #4
Yongzhe Zhang
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For EBU setup, did you use local or global time scale? For rate expression, did you include the products? The code for extinction is not clear, so no idea about it.

The RATE is the reaction rate for leading reactant. For two reactions, the reactants can't be IA at the same time, because the leading reactants must be different for different reactions.

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Old   February 24, 2006, 00:31
Default Re: subroutine reacfn.f
  #5
kris
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I used local time scale and product is as follow

RPFR=MAX(ZERO,Bebu*AMFB/s_prod)

and I'm sorry that I added extinction method.

How can I use variables, such as AMFB,AMFU,AMRC(1) for 2-step reaction?

Aren't there other method that I can get a scalar value

How can I get the scalar values for 2nd step(CO+O2->CO2)?

*******************************************

COMMON/USREAI/IR,NR

COMMON/USREAR/TAUL,TAUG,AEBM,BEBM,AMFU,AMFB,ARCK,BETCK,EACT,

* RTCKF,AMRC(3),RTCKR(3)

DIMENSION SCALAR(50), HFORM(50)

~~~~~~~~abbrev. ~!~~~~~~~~~

EQUIVALENCE( UDAT04(006), P )

EQUIVALENCE( UDAT04(008), TE )

EQUIVALENCE( UDAT04(009), SCALAR(01) )

EQUIVALENCE( UDAT04(059), U )

EQUIVALENCE( UDAT04(060), V )

EQUIVALENCE( UDAT04(061), W )

EQUIVALENCE( UDAT04(062), VISM )

~~~~~~~~abbrev. ~!~~~~~~~~~ ************************************

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