/COM,ANSYS MEDIA REL. 2024R2 (05/10/2024) REF. VERIF. MANUAL: REL. 2024R2 /VERIFY,VM297 /TITLE,VM297,ACOUSTIC PROPOGATION WITH MEAN FLOW IN MUFFLER /COM, /COM, REFERENCE: FINITE ELEMENT AND BOUNDARY ELEMENT MODELLING FOR THE ACOUSTIC WAVE TRANSMISSION /COM, IN MEAN FLOW MEDIUM /COM, T. TSUJI, T. TSUCHIYA, AND Y. KAGAWA /COM, JOURNAL OF SOUND AND VIBRATION (2002) 255(5), 849-866 /COM, /PREP7 L1 = 0.12 ! TOTAL LENGTH OF MUFFLER IN METERS R1 = 0.01 ! RADIUS OF DUCT IN METERS L2 = 0.06 ! LENGTH OF CHAMBER IN METERS R2 = 0.02 ! RADIUS OF CHAMBER IN METERS Z2 = (L1-L2)/2 ! LENGTH OF DUCT IN METERS F1 = 0 ! BEGINING FREQUENCY F2 = 5000 ! ENDING FREQUENCY RHO0=1.2 ! DENSITY IN KG/M^3 C0=340 ! SPEED OF SOUND IN M/S MACH=0.3 ! MACH NUMBER V0=MACH*C0 ! MEAN FLOW VELOCITY IN M/S CYLIND,R1,0,0,L1,0,90 CYLIND,R2,R1,Z2,Z2+L2,0,90 CYLIND,R1,0,0,L1,90,180 CYLIND,R2,R1,Z2,Z2+L2,90,180 CYLIND,R1,0,0,L1,180,270 CYLIND,R2,R1,Z2,Z2+L2,180,270 CYLIND,R1,0,0,L1,270,360 CYLIND,R2,R1,Z2,Z2+L2,270,360 VGLUE,ALL ET,1,FLUID220,,1,,0 ! ACOUSTIC ELEMENT without FSI or PML MP,DENS,1,RHO0 MP,SONC,1,C0 TYPE,1 MAT,1 ESIZE,0.002 /OUT,vm297_SCRATCH VSWEEP,ALL /OUT, NSEL,S,LOC,Z,0 SF,ALL,SHLD,1.0,0 ! APPLY SURFACE VELOCITY LOAD AT INLET NSEL,S,LOC,Z,L1 SF,ALL,INF ! APPLY INFINITE ROBIN RADIATION BOUNDARY AT TERMINAL ALLSEL,ALL BF,ALL,VMEN,0.,0.,V0 ! APPLY UNIFORM MEAN FLOW FOR ACOUSTIC ELEMENT IN Z DIRECTION FINISH /SOLUTION ANTYPE,HARM ! HARMONIC ANALYSIS HARFRQ,F1,F2 ! FREQUENCY RANGE HROPT,FULL KBC,1 NSUB,100 ! NUMBER OF SUBSTEPS DDOPT,FREQ ! FREQUENCY BASED DECOMPOISTION /OUT,vm297_SCRATCH,,,APPEND SOLVE FINISH /POST1 SET,1,40,,3 *GET,P1,NODE,NODE(0,0,0.12),PRES NSEL,S,LOC,X,0 NSEL,R,LOC,Y,0 *GET,_NNOD,NODE,0,COUNT *DIM,NNODE,ARRAY,_NNOD *DIM,ZCORD,ARRAY,_NNOD *DIM,P_AMP,ARRAY,_NNOD *DIM,P_PHA,ARRAY,_NNOD *DO,_I,1,_NNOD NODE=NDNEXT(NODE) NNODE(_I)=NODE *GET,ZL,NODE,NODE,LOC,Z ZCORD(_I)=ZL SET,1,40,,3 ! AMPLITUDE SOLUTION AT 2000HZ *GET,_PA,NODE,NODE,PRES P_AMP(_I)=_PA SET,1,40,,4 ! PHASE ANGLE SOLUTION AT 2000HZ *GET,_PP,NODE,NODE,PRES P_PHA(_I)=_PP *ENDDO /OUT /COM, /COM, NODE ZCORD PRESSURE AMPLITUDE PRESSURE PHASE /COM, *VWRITE,NNODE(1),ZCORD(1),P_AMP(1),P_PHA(1) (2X,F7.0,1X,E12.4,1X,E14.7,1X,E14.7) ALLSEL,ALL /OUT,SCRATCH FINISH /POST26 PRCPLX,1 ! PRINT AMPLTIUDE AND PHASE ANGLE NSEL,S,LOC,Z,L1 ! HARMONIC RESPONSE AT THE TERMINATION END NOD = NDNEXT(0) NSOL,2,NOD,PRES,,PRES PRVAR,2 *GET,RFREQ,VARI,2,EXTREM,TMAX PRVAR,2 /SHOW,PNG,REV PLVAR,2 /SHOW,CLOSE FINISH *DIM,LABEL,CHAR,1,2 *DIM,VALUE,,2,3 LABEL(1,1)='Amp@.12m' LABEL(1,2)='PEAK_FRQ' *VFILL,VALUE(1,1),DATA,1010 ! INTERPOLATED FROM FIGURE.11,PG:860 IN REFERENCE FOR DISTANCE=0.12M,M=0.3 *VFILL,VALUE(1,2),DATA,P1 *VFILL,VALUE(1,3),DATA,ABS(P1/1010) *VFILL,VALUE(2,1),DATA,3000 ! INTERPOLATED FROM FIGURE.12,PG:860 IN REFERENCE,M=0.3 *VFILL,VALUE(2,2),DATA,RFREQ *VFILL,VALUE(2,3),DATA,ABS(RFREQ/3000) /OUT,vm297,vrt /COM, /COM, --------------- RESULT COMPARISON ------------------------------- /COM, /COM, | TARGET | MECHANICAL APDL | RATIO /COM, /COM, ------------------------------------------------------- /COM, PRESSURE AMPLITUDE ALONG THE CENTER LINE FOR Z=0.12m /COM, -------------------------------------------------------- *VWRITE,LABEL(1,1),VALUE(1,1),VALUE(1,2),VALUE(1,3) (1X,A12,' ',F10.3,' ',F14.3,' ',F15.3) /COM /COM, ------------------------------------------------------------- /COM, PEAK RESONANCE FREQUENCY FOR A FREQUENCY RANGE OF 0-5000HZ /COM,-------------------------------------------------------------- /COM, *VWRITE,LABEL(1,2),VALUE(2,1),VALUE(2,2),VALUE(2,3) (1X,A12,' ',F10.3,' ',F14.3,' ',F15.3) /COM, /COM,------------------------------------------------------------------- /OUT, *LIST,vm297,vrt /OUT,SCRATCH,,,APPEND FINISH