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FDS Source: Add diluents to AFT calculation #15136

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Merged
cxp484 merged 2 commits into from
Sep 17, 2025
Merged

FDS Source: Add diluents to AFT calculation #15136

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FDS Source: Add diluents to AFT calculation
cxp484 Sep 15, 2025
d1916b9
Merge remote-tracking branch 'firemodels/master'
cxp484 Sep 17, 2025
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50 changes: 36 additions & 14 deletions Source/fire.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -1187,18 +1187,36 @@ SUBROUTINE CALC_AFT_REAC_AND_PROD(ZZ,ZZ_REAC,ZZ_PROD)
REAL(EB), INTENT(IN) :: ZZ(N_TRACKED_SPECIES)
REAL(EB), INTENT(OUT) :: ZZ_REAC(N_TRACKED_SPECIES),ZZ_PROD(N_TRACKED_SPECIES)
REAL(EB) :: EQUIV, X,Y,Z,A,B,C,D,E, SUM_ZZ

REAL(EB) :: ZZ_MASS, ZZ_FUEL_O2_MASS
REAL(EB) :: REAC_MASS, PROD_MASS, FUEL_MASS, O2_MASS, CO2_MASS, H2O_MASS
INTEGER :: NS

CALL CALC_EQUIV_RATIO(ZZ(1:N_TRACKED_SPECIES), EQUIV)
IF (SIM_MODE /= DNS_MODE .AND. USE_MIXED_ZN_AFT_TMP) THEN
EQUIV = MAX(1.0_EB,EQUIV)
ENDIF

! Based on CxHyOz + a(O2+3.76N2) = bCO2 + cH2O + dCxHyOz + eO2 + 3.76aN2
! Adjust for diluents
ZZ_FUEL_O2_MASS = 0.0_EB
ZZ_MASS = SUM(ZZ(1:N_TRACKED_SPECIES))
ZZ_REAC(1:N_TRACKED_SPECIES) = ZZ(1:N_TRACKED_SPECIES)
ZZ_PROD(1:N_TRACKED_SPECIES) = ZZ(1:N_TRACKED_SPECIES)
DO NS=1, N_TRACKED_SPECIES
IF (SPECIES_MIXTURE(NS)%OXR > 0.0_EB) THEN ! FUEL
ZZ_REAC(NS) = 0.0_EB
ZZ_PROD(NS) = 0.0_EB
ZZ_FUEL_O2_MASS = ZZ_FUEL_O2_MASS + ZZ(NS)
ENDIF
ENDDO
ZZ_REAC(I_O2) = 0.0_EB
ZZ_PROD(I_O2) = 0.0_EB
ZZ_FUEL_O2_MASS = ZZ_FUEL_O2_MASS + ZZ(I_O2)

! Based on CxHyOz + aO2 = bCO2 + cH2O + dCxHyOz + eO2
X=SPECIES_MIXTURE(I_FUEL)%ATOMS(6) !C
Y=SPECIES_MIXTURE(I_FUEL)%ATOMS(1) !H
Z=SPECIES_MIXTURE(I_FUEL)%ATOMS(8) !O
A=0.5_EB*((2.0_EB*X+0.5_EB*Y)/EQUIV -Z)
A=0.5_EB*((2.0_EB*X+0.5_EB*Y)/EQUIV -Z) ! a is a function of equivalence ratio
IF(ABS(EQUIV - 1.0_EB) <1E-3_EB) THEN ! Stoich
B = X
C = 0.5_EB*Y
Expand All @@ -1217,25 +1235,29 @@ SUBROUTINE CALC_AFT_REAC_AND_PROD(ZZ,ZZ_REAC,ZZ_PROD)
ENDIF

! Setup reactants
ZZ_REAC = 0.0_EB
ZZ_REAC(I_FUEL)=1._EB*SPECIES_MIXTURE(I_FUEL)%MW
ZZ_REAC(I_O2)=A*SPECIES_MIXTURE(I_O2)%MW
ZZ_REAC(I_N2)=3.76*A*SPECIES_MIXTURE(I_N2)%MW
FUEL_MASS = 1._EB*SPECIES_MIXTURE(I_FUEL)%MW
O2_MASS = A*SPECIES_MIXTURE(I_O2)%MW
REAC_MASS = FUEL_MASS+O2_MASS
ZZ_REAC(I_FUEL)=FUEL_MASS/REAC_MASS*ZZ_FUEL_O2_MASS
ZZ_REAC(I_O2)=O2_MASS/REAC_MASS*ZZ_FUEL_O2_MASS
SUM_ZZ=SUM(ZZ_REAC)
ZZ_REAC = ZZ_REAC/SUM_ZZ

! Setup products
ZZ_PROD = 0.0_EB
ZZ_PROD(I_CO2)=B*SPECIES_MIXTURE(I_CO2)%MW
ZZ_PROD(I_H2O)=C*SPECIES_MIXTURE(I_H2O)%MW
ZZ_PROD(I_FUEL)=D*SPECIES_MIXTURE(I_FUEL)%MW
ZZ_PROD(I_O2)=E*SPECIES_MIXTURE(I_O2)%MW
ZZ_PROD(I_N2)=3.76_EB*A*SPECIES_MIXTURE(I_N2)%MW
CO2_MASS = B*SPECIES_MIXTURE(I_CO2)%MW
H2O_MASS = C*SPECIES_MIXTURE(I_H2O)%MW
FUEL_MASS = D*SPECIES_MIXTURE(I_FUEL)%MW
O2_MASS = E*SPECIES_MIXTURE(I_O2)%MW
PROD_MASS = CO2_MASS+H2O_MASS+FUEL_MASS+O2_MASS
ZZ_PROD(I_CO2)=ZZ_PROD(I_CO2)+CO2_MASS/PROD_MASS*ZZ_FUEL_O2_MASS
ZZ_PROD(I_H2O)=ZZ_PROD(I_H2O)+H2O_MASS/PROD_MASS*ZZ_FUEL_O2_MASS
ZZ_PROD(I_FUEL)=FUEL_MASS/PROD_MASS*ZZ_FUEL_O2_MASS
ZZ_PROD(I_O2)=O2_MASS/PROD_MASS*ZZ_FUEL_O2_MASS
SUM_ZZ=SUM(ZZ_PROD)
ZZ_PROD = ZZ_PROD/SUM_ZZ


END SUBROUTINE CALC_AFT_REAC_AND_PROD

#endif

SUBROUTINE CHECK_AUTO_IGNITION(EXTINCT,TMP_IN,AIT,IIC,JJC,KKC,REAC_INDEX)
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