TEXT(2D BLUFF-BODY STABILISED METHANE JET TITLE DISPLAY The case considered is 2d steady, axisymmetric, turbulent non-reacting flow behind a bluff-body flame holder. The flow configuration consists of a 5.4mm diameter methane jet seperated from an outer, annular air flow by a 50mm diameter bluff body. The flow is characterised by reverse flow in the annular air stream and exhibits well-defined fuel and annular air stagnation points along the centre-line. This case has been studied experimentally by Schefer et al (Comb.Sci.&Tech., Vol.56, p101, 1987]) and was the subject of an ASCF Ercoftac CFD Workshop (Org: D.Garreton & O.Simonin, EDF, Chatou, France, 1994). ENDDIS The problem requires very high computational resolution for numerical accuracy, and like other disk-related predictions (e.g.McGuirk et al[ 5th TSF, 1985] & Durao et al[ 7thTSF, 1991]) in the literature, the standard k-e model underestimates the size of the recirculation zone, and hence the location of the first stagnation point. The near field of these flows are also known to be sensitive to the inlet conditions. The fuel stagnation point is located 38.7mm downstream of the body while the air stagnation point occurs at about 63mm. * GROUP 1. Run title and other preliminaries * TEXT(2D BLUFF-BODY STABILISED METHANE JET AUTOPLOT USE FILE PHI 5 GDFW.DAT 2 D 1 W1 Y 1;D 2 PLOT;BLB2 2;SCALE X 0 .15;LEVEL X .0441;LEVEL X .0684 LEVEL Y 0. ENDUSE PHOTON USE p 0.20443E+04 0.15633E+04 CR gr ou x 1;vec x 1 sh con w1 x 1 val 1 0. mag gr 2 0.29927E+04 0.90539E+03 CR ENDUSE REAL(RHOAIR,TIN,RAIR,RCON,RHOGAS,DGAS,DBODY,DANN,DTF,ENUAIR) REAL(WGAS,KEGAS,EPGAS,WAIR,KEAIR,EPAIR,WARP,KARP,EPARP) REAL(GYM,GYP,GYDR,GY,GYDR2,GYDR3,GYDR4,GLM,GWI,GEPI,GKI) REAL(Y1,Y2,Y3,Y4,Z1,Z2,RGAS,FRIC,REY,US,US2) INTEGER(NY1,NY2,NY3,NY4,NZ1,NZ2,NYI);CHAR(SCHM) PRESS0=1.01325E5;RAIR=8314.43/29.;TIN=298.;RCON=8314.43/16. ENUAIR=1.58E-5 DGAS=5.4E-3;DBODY=0.05;DANN=0.1;RGAS=0.5*DGAS ** Axial geometry Z1=2.*DANN;NZ1=85 ** Central-jet radial geometry Y1=RGAS;NY1=12 ** Bluff-body radial geometry Y2=0.5*DBODY;NY2=26 ** Annular-jet radial geometry Y3=0.5*DANN;NY3=15 ** External air-stream radial geometry Y4=0.5*(2.*DANN);NY4=12 NYI=NY1+NY2+NY3 ** gas central-jet injection WGAS=21. KEGAS=1.6;EPGAS=1100. RHOGAS=PRESS0/(RCON*TIN) ** air annular-jet injection RHOAIR=PRESS0/(RAIR*TIN) WAIR=25. KEAIR=(0.007*WAIR)**2;EPAIR=0.1643*(KEAIR**1.5)/(0.09*(Y3-Y2)) ** external air stream WARP=0.1;KARP=0.012;EPARP=0.019 REY=WGAS*DGAS/ENUAIR;FRIC=1.0/(1.82*LOG10(REY)-1.64)**2 US=WGAS*(FRIC/8.0)**0.5;US2=US*US KEGAS=2.*US2;EPGAS=0.1643*(KEGAS**1.5)/(0.09*Y1) GROUP 3. X-direction grid specification CARTES=F;XULAST=0.1 GROUP 4. Y-direction grid specification NREGY=4;REGEXT(Y,1) fuel jet IREGY=1;GRDPWR(Y,NY1,Y1,1.0) bluff body IREGY=2;GRDPWR(Y,-NY2,Y2-Y1,1.1) air jet IREGY=3;GRDPWR(Y,-NY3,Y3-Y2,1.1) free stream IREGY=4;GRDPWR(Y,NY4,Y4-Y3,1.4) GROUP 5. Z-direction grid specification GRDPWR(Z,NZ1,Z1,1.3) GROUP 7. Variables stored, solved & named SOLVE(P1,V1,W1,C1);SOLUTN(P1,Y,Y,Y,P,P,P) SOLUTN(V1,P,P,P,P,P,N);SOLUTN(W1,P,P,P,P,P,N) TURMOD(KEMODL);SOLUTN(C1,Y,Y,Y,P,P,N);STORE(ENUT,RHO1) GROUP 8. Terms (in differential equations) & devices MESG( Enter required convection scheme MESG( Default: OSPRE for all variables MESG( The alternative is: MESG( HYB - Hybrid differencing for all variables READVDU(SCHM,CHAR,HOC) CASE :SCHM: OF WHEN HYB,3 + MESG(Hybrid-differencing scheme + DTF=0.1*ZWLAST/WGAS WHEN HOC,3 + MESG(OSPRE for all variables + SCHEME(OSPRE,V1,W1,KE,EP) + DTF=0.01*ZWLAST/WGAS ENDCASE DENPCO=T GROUP 9. Properties of the medium (or media) TMP1=298. RHO1=LINSCAL;RHO1A=RHOAIR;RHO1B=RHOGAS-RHOAIR;RHO1C=16 RHO1=RECSCAL;RHO1A=1./RHOAIR;RHO1B=1./RHOGAS-1./RHOAIR;RHO1C=16 ENUL=ENUAIR;PRT(C1)=0.7 GROUP 10. Inter-phase-transfer processes and properties GROUP 11. Initialization of variable or porosity fields * ** Bluff-body (this could be removed) WALLCO=GRND3 FIINIT(RHO1)=RHOAIR;FIINIT(KE)=KEAIR;FIINIT(EP)=EPAIR GROUP 13. Boundary conditions and special sources * ** Central fuel injection GYM=0. DO JJ=1,NY1 + GYP=YFRAC(JJ)*YVLAST;GY=.5*(GYP+GYM);GYDR=GY/RGAS + GYDR2=GYDR*GYDR;GYDR3=GYDR2*GYDR;GYDR4=GYDR2*GYDR2 + GWI=WGASM*(1.-GYDR)**AN + GWI=WGAS*(1.2342-0.2916*GYDR+0.4809*GYDR2-0.629*GYDR3) + GLM=0.14-0.08*GYDR2-0.06*GYDR4 + GLM=0.5*GLM*DGAS + GKI=1.+2.*GYDR/3.+10.*GYDR3/3.;GKI=GKI*US2 + GEPI=0.1643*GKI**1.5/GLM + PATCH(FU:JJ:,LOW,1,NX,JJ,JJ,1,1,1,1) + COVAL(FU:JJ:,P1,FIXFLU,RHOGAS*GWI) + COVAL(FU:JJ:,V1,ONLYMS,0.0);COVAL(FU:JJ:,W1,ONLYMS,GWI) + COVAL(FU:JJ:,KE,ONLYMS,GKI);COVAL(FU:JJ:,EP,ONLYMS,GEPI) + COVAL(FU:JJ:,C1,ONLYMS,1.0);GYM=GYP ENDDO ** Annular air injection PATCH(AIR,LOW,1,NX,#3,#3,1,1,1,LSTEP) COVAL(AIR,P1,FIXFLU,RHOAIR*WAIR) COVAL(AIR,W1,ONLYMS,WAIR);COVAL(AIR,V1,ONLYMS,0.) COVAL(AIR,KE,ONLYMS,KEAIR);COVAL(AIR,EP,ONLYMS,EPAIR) ** Free stream inlet PATCH(FREEIN,LOW,1,1,#4,#4,1,1,1,LSTEP) COVAL(FREEIN,V1,ONLYMS,0.);COVAL(FREEIN,W1,ONLYMS,WARP) COVAL(FREEIN,P1,FIXFLU,WARP*RHOAIR) COVAL(FREEIN,KE,ONLYMS,KARP);COVAL(FREEIN,EP,ONLYMS,EPARP) ** Exit boundary OUTLET(EXIT,HIGH,1,NX,1,NY,NZ,NZ,1,LSTEP);COVAL(EXIT,P1,10.,0.0) ** Free stream outer boundary PATCH(FREES,NORTH,1,NX,NY,NY,1,NZ,1,LSTEP) COVAL(FREES,P1,10.0,0.0);COVAL(FREES,W1,ONLYMS,WARP) COVAL(FREES,KE,ONLYMS,KARP);COVAL(FREES,EP,ONLYMS,EPARP) ** Low wall boundary on bluff body WALL(BLUFF,LOW,1,NX,#2,#2,1,1,1,LSTEP) GROUP 15. Termination of sweeps LSWEEP=1200 GROUP 17. Under-relaxation devices RELAX(P1,LINRLX,1.0);RELAX(V1,FALSDT,DTF) RELAX(W1,FALSDT,DTF);RELAX(KE,FALSDT,DTF) RELAX(EP,FALSDT,DTF);RELAX(C1,LINRLX,0.5);KELIN=1 GROUP 18. Limits on variables or increments to them VARMIN(C1)=1.E-10;VARMAX(C1)=1.0 GROUP 21. Print-out of variables GROUP 22. Spot-value print-out IXMON=1;IYMON=NY/2;IZMON=NZ-3 GROUP 23. Field print-out and plot control ITABL=3;NPRINT=LSWEEP;TSTSWP=-1;NYPRIN=1 WALPRN=T;NAMGRD=CONV;UCONV=T