1 SUBROUTINE SLOPE(MACH,CLALPA,RENN,XACM) 2C 3C*** CALCULATES AIRFOIL SECTION CLA,CM0 AND XAC 4C 5 COMMON /IBH/ PBH, THN(60),CAM(60),A0,XC,MCC,CLCC 6 COMMON /IBV/ PBV,ZTNU(32),ZCNU(32),ST1NU(32),ST2NU(32), 7 1 ST3NU(32),ST4NU(32),ST5NU(32),X(32),THNU(32), 8 2 THMU(32) 9 COMMON /IBWH/ PBWH,AI,ALO,CLI,ALPMAX,CMCO4 10 COMMON /IBWHV/ PBWHV,RHO 11 COMMON /CONSNT/ PI,DEG,UNUSED,RAD 12 COMMON /IPOWER/ PP,VXOVU(32),VXOVL(32),CPUM(32),CPLM(32), 13 1 BO(32),CPI(32) 14 DIMENSION CL(2),ALPHA(2),CM(2),XI(32),STNU(32) 15C 16C WEBER PRESSURE DISTRIBUTION AND CL-ALPHA 17C METHOD INCLUDES COMPRESSIBILITY 18C 19 REAL LX,MACH,MCC 20 XN=32. 21 N=XN 22 NM1=N-1 23 CLALPA=UNUSED 24 IF(MACH.GE.1.) GO TO 1070 25 ALPHA(1)=ALO 26 ALPHA(2)=ALO+1. 27 BETA=SQRT(1.-MACH**2) 28 A0=SQRT(2.*RHO) 29 TMACH=0. 30 IF(MACH.NE.0.) TMACH=1./(.7*MACH**2) 31 1000 DO 1050 I=1,2 32 COSA=COS(ALPHA(I)*DEG) 33 SINA=SIN(ALPHA(I)*DEG) 34 DO 1020 L=1,NM1 35 CPI(L)=1.-(1.+ST1NU(L))**2/(1.+ST2NU(L)**2) 36 BO(L)=1.-MACH**2*(1.-MACH*CPI(L)) 37 IF(BO(L) .LT. 0.) GO TO 1080 38 BO(L)=SQRT(BO(L)) 39 VXOVU(L)=(COSA*(1.+ST1NU(L)/BO(L)+ST4NU(L)/BETA)+SINA/BETA* 40 1 (1.+ST3NU(L)/BO(L))*SQRT((1.-X(L))/X(L)))/SQRT(1. 41 2 +((ST2NU(L)+ST5NU(L))/BO(L))**2) 42 VXOVL(L)=(COSA*(1.+ST1NU(L)/BO(L)-ST4NU(L)/BETA)-SINA/BETA* 43 1 (1.+ST3NU(L)/BO(L))*SQRT((1.-X(L))/X(L)))/SQRT(1. 44 2 +((ST2NU(L)-ST5NU(L))/BO(L))**2) 45 IF(MACH .EQ. 0.) GO TO 1010 46 CPUVD=1.+.2*MACH**2*(1.-VXOVU(L)**2) 47 IF(CPUVD .LT. 0.) GO TO 1080 48 CPLVD=1.+.2*MACH**2*(1.-VXOVL(L)**2) 49 IF(CPLVD .LT. 0.) GO TO 1080 50 CPUM(L)=TMACH*((CPUVD)**(3.5)-1.) 51 CPLM(L)=TMACH*((CPLVD)**(3.5)-1.) 52 GO TO 1020 53 1010 CPUM(L)=1.-(VXOVU(L))**2 54 CPLM(L)=1.-(VXOVL(L))**2 55 1020 CONTINUE 56C 57C PRESSURE COEFFICIENT AT THE LEADING EDGE 58C 59 IF(A0.NE.0.)VXOVU(N)=SINA*((1.+ST3NU(N))/(.5*A0)) 60 IF(A0.EQ.0.)VXOVU(N)=0. 61 VXOVL(N)=VXOVU(N) 62 CPUVDN=1.+.2*MACH**2*(1.-(VXOVU(N)/BETA)**2) 63 IF(CPUVDN .LT. 0.) GO TO 1080 64 CPUM(N)=TMACH*((CPUVDN)**(3.5)-1.) 65 IF(TMACH .EQ. 0.) CPUM(N)=1.-(VXOVU(N))**2 66 CPLM(N)=CPUM(N) 67C 68C INTEGRATE THE CP CURVE AT THIS ALPHA 69C 70 SUMCL=0.0 71 DO 1030 L=1,NM1 72 LX=-(CPUM(L)-CPLM(L)) 73 SINTH=SIN(THNU(L))/2. 74 SUMCL=SUMCL+LX*SINTH 75 1030 CONTINUE 76 CL(I)=SUMCL*PI/(COSA*XN) 77C 78C PITCHING MOMENT COEFFICIENT 79C 80 SUMCM=0.0 81 DO 1040 L=1,NM1 82 LX=CPUM(L)-CPLM(L) 83 DCM=LX*(X(L)-.25)*SIN(THNU(L))/2. 84 1040 SUMCM=SUMCM+DCM 85 CM(I)=SUMCM*PI/XN 86 1050 CONTINUE 87 IF(ABS(CL(1)) .LE. .001) GO TO 1060 88 CLALPA=CL(2)-CL(1) 89 ALO=ALO-CL(1)/CLALPA 90 ALPHA(1)=ALO 91 ALPHA(2)=ALO+1. 92 GO TO 1000 93 1060 CONTINUE 94C 95C GET CORRECTION FACTOR FOR VISCOUS AFFECTS 96C 97 REN=1.E6 98 IF (RENN.GE.10..AND.MCC.NE.0..AND.MACH.NE.0.) REN=RENN 99 IF(REN .LT. 2.71828E5)WRITE(6,1170) 100 IF(REN .LT. 2.71828E5)REN=2.7182E5 101 PHITE=((ZTNU(6)+ZTNU(7))/2.-ZTNU(2))/.089272624 102 EXPN=-1.+5.*PHITE/2. 103 CON=1.-(ALOG(REN /1.E5))**EXPN*(.232+1.785*PHITE-2.950*PHITE**2) 104 IF(CON .LT. .6896) CON=.6896 105C 106C GET LIFT CURVE SLOPE FROM THESE TWO ANGLES OF ATTACK 107C 108 CLALPA=(CL(2)-CL(1))*CON*1.05 109C 110C GET PITCHING MOMENT SLOPE 111C 112 CMALPA=CM(2)-CM(1) 113 IF(MACH.EQ.0.0) CMCO4=CM(1) 114C 115C NOW THE AERODYNAMIC CENTER 116C 117 XACM=0.25-CMALPA/CLALPA 118 1070 CONTINUE 119 GO TO 1090 120 1080 CONTINUE 121C 122C ANALYSIS FAILING -- PRINT INFORMATIVE DIAGNOSTIC 123C 124 WRITE(6,1160) 125 1090 CONTINUE 126 IF(MACH .NE. 0.) GO TO 1150 127C 128C CALCULATE THE CREST CRITICAL CONDITIONS FOR THIS AIRFOIL 129C 130 CLM=CLALPA 131 J=N-1 132 DO 1100 I=1,NM1 133 XI(I)=X(J) 134 STNU(I)=ST2NU(J)+ST5NU(J) 135 1100 J=J-1 136 STC=SINA/COSA 137 DO 1110 I=1,NM1 138 II=I 139 IF(STC .GT. STNU(I)) GO TO 1120 140 1110 CONTINUE 141 1120 XC=(STC-STNU(II))/(STNU(II-1)-STNU(II))*(XI(II-1)-XI(II))+XI(II) 142 DO 1130 I=1,NM1 143 II=I 144 IF(XC .GT. X(I)) GO TO 1140 145 1130 CONTINUE 146 1140 VOVU=(XC-X(II))/(X(II-1)-X(II))*(VXOVU(II-1)-VXOVU(II))+VXOVU(II) 147 CPCC=1.-VOVU**2 148 MCC=1.023-.9507*CPCC-.4140*CPCC**2-.1506*CPCC**3-.0212*CPCC**4 149 MCC=1./MCC 150 BCC=SQRT(1.-MCC**2) 151 CLCC=(ABS(CLM)/(BCC-(MCC**2/(1.+BCC))*ABS(CLM)/2.))*CON 152 1150 CONTINUE 153 1160 FORMAT(56H ********* COMPUTATIONS IN SUBROUTINE SLOPE HAVE FAILED. 154 1,38H ANALYSIS FOR THIS AIRFOIL IMPOSSIBLE.) 155 1170 FORMAT(56H0**** REYNOLDS NUMBER TOO LOW FOR THE AIRFOIL SECTION MO 156 1,61HDULE, SECTION CHARACTERISTICS BASED ON A VALUE OF 2.718E5 ***) 157 RETURN 158 END 159