TALK=T;RUN( 1, 1) ** LOAD(x302) from the x Input Library TEXT(Owen Furnace CH4 Diffusion Flame TITLE DISPLAY The case considered is the zero-swirl gas-fired axisymmetric combustion chamber used in the experiments of Owen et al ( 16th Int. Symp. on Combustion, p105-117, 1976). The geometry comprises a 0.122m diameter tube into which natural gas (96%CH4) is injected at 288K axially to mix and burn with a coaxial annular air stream at 750K. The inlet air/fuel equivalence ratio is 0.9, and the combustor operating pressure is 3.8 atm. The length of the solution domain is taken as 4 furnace diameters. Calculations are made with one of 4 different combustion models: (a) fast-chemistry model with a 1-step global irreversible methane reaction to form CO2 and H2O; (b) as (a) but with an assumed double-delta pdf to account for the influence of concentration fluctuations; (c) eddy-break-up finite-rate chemistry model with a 1-step global irreversible reaction; and (d) as (c) but with a 2-step global reaction mechanism involving the intermediate CO. Radiative heat transfer is modelled via the P1 spherical-harmonics approximation for a gray medium. ENDDIS GROUP 1. Run title and other preliminaries CHAR(CMOD);BOOLEAN(THRAD) REAL(MDOTF,MDOTA,RJETF,ROUTA,TINA,TINF,WINF,WINA,KEINT,EPINT) REAL(KFUEL,EFUEL,KAIR,EAIR,DENF,DENA,PI,AREAF,AREAA,DIAM) REAL(YFUIN,YOXIN,YN2IN,WFUEL,WAIR,UGASC,RTUBE,PATM) MDOTF=7.2E-3;MDOTA=137.E-3;YFUIN=1.0;YOXIN=0.232;YN2IN=1.-YOXIN RJETF=3.15E-2; ROUTA=4.75E-2; RTUBE=6.1E-2;DIAM=2.*RTUBE TINA=750.;TINF=288.;PATM=1.01325E5;PI=3.1415926;WFUEL=16.04 WAIR=28.84;UGASC=8413.43 PRESS0=3.8*PATM AREAF=PI*RJETF*RJETF;AREAA=PI*(ROUTA*ROUTA-RJETF*RJETF) MDOTF=7.2E-3;MDOTA=137.E-3 DENF=PRESS0*WFUEL/(UGASC*TINF);DENA=PRESS0*WAIR/(UGASC*TINA) WINF=MDOTF/(DENF*AREAF);WINA=MDOTA/(DENA*AREAA) KFUEL=(0.2*WINF)**2;KAIR=(0.2*WINA)**2 EFUEL=0.1643*KFUEL**1.5/(0.1*RJETF) EAIR=0.1643*KAIR**1.5/(0.1*(ROUTA-RJETF)) MESG( Thermal radiation ? (default=N) READVDU(ANS,CHAR,N) IF(:ANS:.EQ.Y) THEN + THRAD=T + MESG( Thermal Radiation activated ELSE + THRAD=F ENDIF GROUP 2. Transience; time-step specification STEADY=T GROUP 3. X-direction grid specification CARTES=F;XULAST=0.1 GROUP 4. Y-direction grid specification NREGY=3 IREGY=1;GRDPWR(Y,10,RJETF,1.0) IREGY=2;GRDPWR(Y,10,ROUTA-RJETF,1.0) IREGY=3;GRDPWR(Y,10,RTUBE-ROUTA,1.0) GROUP 5. Z-direction grid specification NREGZ=1 IREGZ=1;GRDPWR(Z,40,0.5,1.4) GROUP 7. Variables stored, solved & named SOLVE(P1,V1,W1);STORE(VIST,DEN1,TMP1) SOLUTN(P1,P,P,Y,P,P,P);SOLUTN(V1,P,P,P,P,P,N) SOLUTN(W1,P,P,P,P,P,N);TURMOD(KEMODL) GROUP 8. Terms (in differential equations) & devices ENUL=4.2E-5 GROUP 9. Properties of the medium (or media) *** START OF EXTENDED SCRS MODEL SETTINGS CFUEL=CH4 COXID=O2 CFP1=CO2 CFP2=H2O NRSYS=-2 INTEGER(NSPEC,NELEM);NSPEC=7;NELEM=4 INTEGER(ICOMB,NCSTEP,NCREAC) MESG( Enter required combustion model MESG( Default: 1 step finite rate EBU MESG( The options are: MESG( EBU1 - 1 step finite-rate EBU MESG( EBU2 - 2 step finite-rate EBU MESG( BURN - Infinite-rate model MESG( DDEL - Infinite-rate model with Double-Delta PDF READVDU(CMOD,CHAR,EBU1) CASE :CMOD: OF WHEN EBU1,4 + MESG(1 step finite-rate EBU model + NCSTEP=1;NCREAC=1;ICOMB=0 + SCRS(SYSTEM,NCSTEP,NCREAC,NELEM,FRATE*) + SCRS(SPECIES,CH4,O2,H2,CO,H2O,CO2,N2) + SCRS(PROP,CHEMKIN,SCH4) + SCRS(EBU,P,6.0) + STORE(P1RS) WHEN EBU2,4 + MESG(2 step finite-rate EBU model + NCSTEP=2;NCREAC=2;ICOMB=1 + SCRS(SYSTEM,NCSTEP,NCREAC,NELEM,FRATE*) + SCRS(SPECIES,CH4,O2,H2,CO,H2O,CO2,N2) + SCRS(PROP,CHEMKIN,STWO) + SCRS(EBU,P,6.0);SCRS(EBU,S1,1.0) + STORE(P1RS,S1RS) WHEN BURN,4 + MESG(Infinite rate model + NCSTEP=1;NCREAC=1;ICOMB=2 + SCRS(SYSTEM,NCSTEP,NCREAC,NELEM,FASTC) + SCRS(SPECIES,CH4,O2,H2,CO,H2O,CO2,N2) + SCRS(PROP,CHEMKIN,SCH4) WHEN DDEL,4 + MESG(Infinite-rate model with Double-Delta PDF + NCSTEP=1;NCREAC=1;ICOMB=3 + SCRS(SYSTEM,NCSTEP,NCREAC,NELEM,FASTC) + SCRS(SPECIES,CH4,O2,H2,CO,H2O,CO2,N2) + SCRS(PROP,CHEMKIN,SCH4) + SCRS(PDF,DDELTA) ENDCASE STORE(MMWT,MCO,MCO2) ** Define fuel & oxidiser composition & temperature SCRS(FUIN,YFUIN,0.0,0.0,0.0,0.0,0.0,0.0,TINF) SCRS(OXIN,0.0,YOXIN,0.0,0.0,0.0,0.0,YN2IN,TINA) *** END OF EXTENDED SCRS MODEL SETTINGS IF(THRAD) THEN + REAL(ABSORB,SCAT,SIGMA,EMPW,EMISW,EMISG,EMPG,TWAL,TGUES) + ABSORB=0.25/DIAM;SCAT=0.; EMISG=0.07;TWAL=600.;TGUES=600. + SIGMA=5.6697E-8; EMISW=0.9 + EMPW=SIGMA*TWAL**4; EMPG=SIGMA*EMISG*TGUES**4 + RADIAT(RADI,ABSORB,SCAT,H1) + SOLUTN(SRAD,P,P,Y,P,P,P);SOLUTN(H1,P,P,N,P,P,P) IF(ICOMB.GT.1) THEN + SOLUTN(SRAD,P,P,N,P,P,P); ENDIF ELSE + STORE(H1,SRAD) ENDIF GROUP 11. Initialization of variable or porosity fields INIADD=F KEINT=(0.15*WINA)**2; EPINT=0.1643*KEINT**1.5/(0.1*RTUBE) FIINIT(W1)=WINA; FIINIT(KE)=KEINT; FIINIT(EP)=EPINT FIINIT(H1)=4.724E5 FIINIT(TMP1)=TINA;FIINIT(F)=0.0;FIINIT(DEN1)=DENA IF(THRAD) THEN + FIINIT(SRAD)=EMPG; FIINIT(H1)=4.72E5 ENDIF GROUP 13. Boundary conditions and special sources * FUEL-STREAM INLET boundary condition INLET(SCRSF,LOW,1,NX,#1,#1,1,1,1,1) VALUE(SCRSF,P1,GRND1); VALUE(SCRSF,W1,WINF) VALUE(SCRSF,EP,EFUEL); VALUE(SCRSF,KE,KFUEL) VALUE(SCRSF,F,1.); VALUE(SCRSF,CH4,YFUIN) IF(THRAD) THEN + VALUE(SCRSF,H1,GRND3) ENDIF * AIR-STREAM INLET boundary condition INLET(SCRSO,LOW,1,NX,#2,#2,1,1,1,1) VALUE(SCRSO,P1,GRND1); VALUE(SCRSO,W1,WINA) VALUE(SCRSO,EP,EAIR); VALUE(SCRSO,KE,KAIR) VALUE(SCRSO,F,0.) IF(THRAD) THEN + VALUE(SCRSO,H1,GRND3) ENDIF PATCH(OUT,HIGH,1,NX,1,NY,#NREGZ,#NREGZ,1,1) COVAL(OUT,P1,1.E2,0.);COVAL(OUT,F,ONLYMS,SAME) IF(THRAD) THEN + VALUE(OUT,H1,SAME) ENDIF * WALL boundary condition PATCH(NWALL3,NWALL,1,NX,#NREGY,#NREGY,1,NZ,1,1) COVAL(NWALL3,W1,GRND2,0.0);COVAL(NWALL3,KE,GRND2,GRND2) COVAL(NWALL3,EP,GRND2,GRND2) IF(THRAD) THEN + PATCH(NWALL3R,NORTH,1,NX,#NREGY,#NREGY,1,NZ,#1,1) + COVAL(NWALL3R,SRAD,2.*EMISW/(2.0-EMISW),EMPW) + PATCH(LWALL3R,LOW,1,NX,#3,#3,1,1,#1,1) + COVAL(LWALL3R,SRAD,2.*EMISW/(2.0-EMISW),EMPW) ENDIF GROUP 15. Termination of sweeps LSWEEP=600 GROUP 16. Termination of iterations GROUP 17. Under-relaxation devices REAL(DTF);DTF=ZWLAST/NZ/WINA RELAX(P1,LINRLX,0.5); RELAX(V1,FALSDT,DTF) RELAX(W1,FALSDT,DTF); RELAX(KE,LINRLX,0.5) RELAX(EP,LINRLX,0.5); KELIN = 3 RELAX(F,LINRLX,0.5) ; RELAX(DEN1,LINRLX,0.01) IF(ICOMB.EQ.0) THEN * 1 step finite-rate EBU model (ICOMB=0) + RELAX(CH4,FALSDT,0.5*DTF) ENDIF IF(ICOMB.EQ.1) THEN * 2 step finite-rate EBU model (ICOMB=1) + RELAX(CH4,FALSDT,0.5*DTF);RELAX(CO,FALSDT,0.5*DTF) ENDIF IF(THRAD) THEN + RELAX(H1,FALSDT,20.*DTF); RELAX(SRAD,FALSDT,20.*DTF) IF(ICOMB.EQ.2) THEN *** Infinite-rate model with radiation + LSWEEP=1000 + RELAX(v1,FALSDT,5.*DTF);RELAX(W1,FALSDT,5.*DTF) + RELAX(H1,FALSDT,DTF); RELAX(SRAD,FALSDT,DTF) + RELAX(DEN1,LINRLX,1.E-4) ENDIF IF(ICOMB.EQ.3) THEN *** Infinite-rate model with Double-Delta PDF & radiation + LSWEEP=800 + RELAX(H1,FALSDT,2.*DTF); RELAX(SRAD,FALSDT,2.*DTF) ENDIF ENDIF GROUP 18. Limits on variables or increments to them VARMIN(DEN1)=1.E-10 VARMAX(F)=1.0;VARMIN(F)=1.0E-10 IF(ICOMB.EQ.3) THEN * Infinite-rate model with Double-Delta PDF + RELAX(FSQ,LINRLX,0.5) + VARMIN(FSQ)=1.E-10 ENDIF GROUP 20. Preliminary print-out ECHO=T GROUP 21. Print-out of variables TSTSWP=-1 OUTPUT(TMP1,P,P,P,P,Y,Y); OUTPUT(DEN1,P,P,P,P,Y,Y) GROUP 22. Spot-value print-out IXMON=1;IYMON=2;IZMON=6 GROUP 23. Field print-out and plot control GROUP 24. Dumps for restarts RESTRT(P1,V1,W1,KE,EP,H1,TMP1,DEN1,VIST,F) RESTRT(CH4,O2,H2,CO,H2O,CO2,N2,SPH1) LIBREF = 302 print-out of mass average values elicited by spedat SPEDAT(PRINT,NUMBER,I,10) SPEDAT(PRINT,COMMAND1,C,AVE_DEN1) SPEDAT(PRINT,COMMAND2,C,AVE_P1) SPEDAT(PRINT,COMMAND3,C,AVE_TMP1) SPEDAT(PRINT,COMMAND4,C,AVE_F) SPEDAT(PRINT,COMMAND5,C,AVE_V1) SPEDAT(PRINT,COMMAND6,C,AVE_W1) SPEDAT(PRINT,COMMAND7,C,AVE_EP) SPEDAT(PRINT,COMMAND8,C,AVE_KE) SPEDAT(PRINT,COMMAND9,C,AVE_VIST) SPEDAT(PRINT,COMMAND10,C,AVE_H1) STOP