Merge pull request #15116 from cxp484/master

FDS Source: LES AFT calculation modification

Author: cxp484

Source/fire.f90

@@ -1182,13 +1182,17 @@ END SUBROUTINE CALC_ADIABATIC_FLAME_TEMPERATURE
 ! Calculate Reactants and products
 SUBROUTINE CALC_AFT_REAC_AND_PROD(ZZ,ZZ_REAC,ZZ_PROD)
 USE PHYSICAL_FUNCTIONS, ONLY: CALC_EQUIV_RATIO
-USE CHEMCONS, ONLY: I_FUEL,I_CO2,I_H2O,I_O2,I_N2
+USE CHEMCONS, ONLY: I_FUEL,I_CO2,I_H2O,I_O2,I_N2,USE_MIXED_ZN_AFT_TMP
+
 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
 
 
 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
 X=SPECIES_MIXTURE(I_FUEL)%ATOMS(6) !C