In order to meet the need for propulsion testing in the high supersonic range from Mach 4 to Mach 7, NASA has undertaken the modification of the Langley Eight Foot High Temperature Tunnel to add alternate Mach number capability and oxygen enrichment to allow the testing of operating engines at these Mach numbers and at true temperature tunnel. The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine generally requires the use of a pressurizing gas at high pressures. Although nitrogen is preferred, unfortunately, when gaseous nitrogen (GN2) is used as the pressurant to transfer liquid oxygen from a storage tank to the tunnel combustor, it contaminates the liquid oxygen and effects a loss of performance in the engine. The contamination of the LOX by the pressurizing GN2 is described, which may prove to be an important operational constraint. It is desirable to have reliable data concerning the penetration of GN2 into LOX during pressurization and the subsequent of self cleaning after blowdown

Mielke, Roland R.

Ngo, Kim Chi

English

NASA Technical Reports Server

# 
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING 
COLLEGE OF ENGINEERING AND TECHNOLOGY 
OLD D O M I N I O N  U N I V E R S I T Y  
NORFOLK, V I R G I N I A  23508 
I 
SUPPORT OF THE EIGHT-FOOT HIGH TEMPERATURE 
TUNNEL MODIFICATION PROJECT 
BY 
K i m  Chi Ngo, Undergraduate Research A s s i s t a n t  
and 
Roland R. Mielke, P r i n c i p a l  I n v e s t i g a t o r  
F i n a l  Report 
For  t h e  p e r i o d  ended August 16, 1987 
Prepared f o r  the 
Nat iona l  Aeronautics and Space Admin i s t ra t i on  
Langley Reseach Center 
Hampton, V i r g i n i a  23665 
Under 
Master Contract Agreement NAS1-17993 
Task Authorization No. 66 
D r .  A l l a n  J. Zuckerwar, Technical  Mon i to r  
IRD-Acoustics and V i  b r a t  i o n  Instrument a t  i o n  Sect i o n  
Submitted by the 
Old Dominion University Research Foundation 
P. 0. Box 6369 
Norfolk, V i rg in ia  23508 
August 1987 * 
https://ntrs.nasa.gov/search.jsp?R=19870018245 2020-03-20T10:11:54+00:00Z
SUPPORT OF THE EIGHT-FOOT HIGH TEMPERATURE TUNNEL WIIFICATION PROJECT 
BY 
K i m  Chi Ngol and Roland R.  Mielke2 
LIQUID OXYGEN-LIQUID NITROGEN MIXING AND SELF-CLEANING STUDY 
INTRODUCTION 
In the past several years, there has been a resurgent interest  i n  hy- 
personics. In order t o  meet the need for propuls ion testing i n  the h i g h  
superson!c range f r m  Mach 4 t o  Mach 7, ::?\SA has iindzi-takzii the modi f ica t ion  
of the Langley Eight-Foot High Temperature Tunnel t o  add alternate Mach 
number capability and add oxygen enrichment t o  allow the tes t ing of oper- 
a t i n g  engines a t  these Mach numbers and a t  true temperature tunnel. 
The transfer of l i q u i d  oxygen (LOX) from a storage vessel t o  a rocket 
engine generally requires the use of  a pressurizing gas a t  h i g h  pressures. 
Among the common gases, helium, oxygen, and nitrogen have been considered. 
However, helium is  expensive, and oxygen i s  hazardous a t  h i g h  pressures. 
Therefore, nitrogen is  preferred. Unfortunately, when gaseous nitrogen 
( G N 2 )  is used as the pressurant t o  t ransfer l i q u i d  oxygen from a storage 
tank t o  the tunnel combustor, i t  contaminates the l i q u i d  oxygen and effects  
a loss of performance i n  the engine. 
-9 The purpose of this study is  t o  describe the contamination of the LOX 
by the pressurizing GN2,  which may prove t o  be an important operational 
constraint. I t  is desirable t o  have rel iable  d a t a  concerning the pene- 
t r a t i o n  of G N 2  i n t o  LOX d u r i n g  pressurization and the subsequent o f  se l f -  
cleaning af ter  "blowdown." 
Undergraduate Research Assistant, Department o f  Electrical and Computer 
Engineering, Old Dominion University, Norfolk, Virginia  23508. 
Dominion University, Norfolk, Virginia 23508. 
2Chairman/Professor, Department of Electrical and Computer Engineering, 01 d 
EXPERIMENTAL PROCEDURE 
The experiment was c a r r i e d  ou t  a t  t h e  7" Mach Seven Tunnel, t h e  p i l o t  
tunnel  f o r  t he  8 Foot High Temperature Tunnel. The LOX-LN2 contamination 
experimental set-up i s  shown i n  Appendix A, and the  experimental procedure 
i s  i l l u s t r a t e d  i n  Fig. 1. 
F i r s t ,  t h e  2-gal lon c y l i n d r i c a l  vessel was f i l l e d  t o  a l e v e l  o f  46 inches 
w i t h  LOX, as measured by a nuclear monitor. A t  t h i s  p o i n t  t h e  LOX was pres- 
sur ized by GN2 and he ld  a t  a spec i f i c  pressure f o r  a per iod  o f  t ime. Sec- 
ondly, a f te r  t he  pressur iza t ion  was completed, t he  n i t rogen  was blown down 
t o  0 psig.  
a 100% Beckman Oxyen Analyzer. The data were taken by  an analog t o  d i g i t a l  
conver ter  i n  an Apple I1 
analog inst runentat ion.  
The t e s t  procedure consisted of th ree  steps. 
F ina l l y ,  t he  evaporating l i q u i d  from t h e  tank was vented through 
+ 
computer, which records the  reading from the  
RESULTS AND ARALYSIS 
The i n t e r p r e t a t i o n  o f  t h e  experimental r e s u l t s  i s  based on the  fo l low-  
i n g  model : 
1) During pressur iza t ion  Np 
u l  ar d i f f u s i o n .  
2)  The depth o f  penet ra t ion  
penetrates i n t o  the  LOX by simple molec- 
depends upon the  GN2 pressure, which 
determines the  surface concentration, and t h e  ho ld ing  t ime. 
A f t e r  blowdown t h e  l i q u i d  evaporates. A t  any given t ime the  compo- 
s i t i o n  o f  t he  evaporat ing l i q u i d  r e f l e c t s  the  concentrat ion p r o f i l e  
estab l ished i n  the  l i q u i d  by d i f f u s i o n .  
3 )  
To analyze t h i s  experiment, the f i r s t  step i s  t o  der ive  the  c o n t i n u i t y  
lage volume. This  we l l  known equat ion fo r  t he  nmber  o f  GI$ moles i n  t h e  
concentrat ion p r o f i l e  due t o  d i f f u s i o n  equation can be w r i t t e n  as: 
2 
c 
0 
U 
0 
m 
3 
3 -
n cu. 
c 
0 
I 1  
N C V  
7 7  X 0 
aJ 
L 
3 
-0 a 
V 
0 
L a 
c, 
v) 
aJ 
c, 
3 
dxn R Zo R V L t  
nT dt + R Xn = [ 1- e r f  (- + -)] 
h Ah 
where 
nT: 
x :  n 
R: 
V L: 
A: 
Zo/h: s t a r t i n g  depth penetrat ion 
e r f (  x)  : 
the  nunber o f  moles o f  N2 a t  t ime  t 
the  instantaneous mole f r a c t i o n  N2 i n  t h e  l i q u i d  
the  evaporation r a t e  i n  mole/sec 
the  molar volume o f  the  l i q u i d  
the  cross sec t iona l  area o f  t h e  dewar 
e r r o r  funct ion o f  x 
s ince 
- Ah - 
T2 - 
RVL 
s u b s t i t u t e  Eqs. ( 2 )  and ( 3 ) ,  i n to  Eq. (4 ) ,  i t  y i e l d s  i n  t h e  form as: 
dxn 1 - 1 ZO 
- + -  X, - - [ 1- e r f  ( t /T2  + 4 3 .  
d t  T~ h 
2T 1 
( 4 )  
By using the Laplace transform t o  solve f o r  t he  d i f f e r e n t i a l  Eq. ( 4 ) ,  t h e  
s o l u t i o n  o f  t he  c o n t i n u i t y  equation can be w r i t t e n  as: 
4 
1 
2 
- - [ E r f  ( t / T 2  + 
1 +, 
2 
- E r f  (- zo - -)] '2 
h 2r; 
where 
1 zo t X = - [ I  - E r f  (-++]j. 
no 2 '2 
Using a b e s t - f i t  procedure, one can determine t h e  values f o r  t he  t ime 
constants T~ and T~ f o r  each t e s t .  
P l o t s  of t he  data and Eq. (5 )  us ing p re l im ina ry  estimates o f  and T~ 
are shown i n  Figs. 2, 3, 4 and 5. Once the  values o f  t l  and T~ were estab- 
l ished, the  ev,aporation r a t e  R and t h e  penet ra t ion  depth can be determined 
from Eqs. (2 )  and ( 3 ) .  
ENTERDATA, PLOTDATA, BEST-FIT, and SUMT2 are t h e  f o u r  computer s o f t -  
wares which were w r i t t e n  i n  the  B A S I C  t o  analyze the  experiment. 
f lowcharts and the  programs are l i s t e d  i n  t h e  Appendixes B, C, D, and E. 
The 
CONCLUSION 
As of t h i s  w r i t i n g  the  f i n a l  data analys is  i s  no t  y e t  completed, bu t  
p re l im ina ry  analys is  ind ica tes  that a t  t he  low pressure < 1000 ps i ,  t he  
5 
c) 
t 
5 l n  
m 
c 3 w  
.. m 
3 5 ,  
'ZN 
.I- .I- -- 
0 
0 
0 
.. 
v) 
> 
V 
L 
W 
CL 
a 
E 
Ll 
CI 
+ 
t 
m 
w' x 
c CI 
v) > 
2 
W u 
C 
K c 
t 
w' u 
f 
Lu c 
m 
7 
z 
z 
m 
m 
Iy 
I 
0 
CI 
c 
- 
3 
a z 
u 
Q 
2 
aJ 
E 
.I- 
7 
U aJ 
L 
3 
v) 
5 
aaJ 
m .. v) 
aJaJ 
E N  
?? 
0 
5 %  
3 v )  
22 
E: 
aJ 
0 7  
0 
L 
8 
L. 
n 
Q 
c 
E 
5 
V 
0 a c 
I- 
2 
Y 
L, 
I, a 
a 
aJ 
E 
-a aJ 
L 
7 
v) 
5 a 
E *r 
m 
3 
5 %  
3f 
9 
depth penetrat ion i s  very  small. In some tes ts ,  t he re  were evidences t h a t  
LN2 was a t  t h e  bottom of t he  vessel. It i s  hoped t h a t  t he  add i t i ona l  
t e s t i n g  can be undertaken a t  7" Mach Seven Tunnel i n  t h e  near f u t u r e  t o  
f u l l y  de f ine  the  s ign i f i cances  o f  the evaporation r a t e  and t h e  depth 
penetrat ion o f  GN2 i n t o  LOX dur ing pressur izat ion.  
REFERENCES 
1. Al lan  J. Zuckerwar, "Prel iminary Study o f  Gaseous Nitrogen-Liquid Oxy- 
gen Mixing and Self-Cleaning," NASA Technical Memorandum 87658, Decem- 
ber 1985. 
. -  
lo 
APPENDIX A 
LOX-LN2 CONTAMINATION EXPERIMENTAL SET-UP 
U 
c c a > 
-t 
0- 
I 
.- 
I 
rn c .- 
U 
rn 
X 
Lu 
.- 
LOX Contamination Monitoring Test DI-- Date 
A.  Set Up Procedure 
1. Instal 1 connector for cool ing coi 1 2. 
2. Cap off run tank. 
3. Connect values 3409X and 342% to monitoring system. 
4. Install and check out nuclear monitor. Locate at 46 
5. Cal i brate Beckmann 02 Analyzer. 
6. Close values "A", "B' ,  "C', and " D " .  
inches. 
6 .  Precool i ng Procedure 
1. Open value " A . "  
3. Drain LN2. 
4 .  Run LN2 through cooling coils 1 and 2. 
5. Follow existing checklist for "LOX Transfer 
6. Fill to 46 inches, a5 observed on nuclear monitor. 
7. Wait - min. 
2. Fo? ? 9-e ex I s t  i ns check! i st +=!- " ! h = l  de&!!? w i  t!? L.h!2. " 
Operat ion. " 
C. Pressur i tat i on and B1 owdown Procedure 
1 .  C1 ose ual ue "A: 
2. Follow existing checklist for pressurizing with GN2 to 
3. Maintain pressure far - min. 
4 .  Close 343tN. 
5. Open 3411N. 
6. Open ualue 341W to vent pressure. 
psi. 
D. GO2 Monitoring Procedure 
1. Close value 3 4 1 s  at 0 psi. 
2. Close 3410N. (3411N optional). 
3. Open ualue 3409X. 
4.  Open value " A " .  NOTE: This insures that pressurized 
GN2 is completely blown down. 
5. Open value "C". 
6. Adjust ualue "B" until flow rate reads 
7. Monitor thermocouple, Beckmann, 02 pressure, and both 
units. 
f 1 Owme ter readings con t i nuousl Y .  
E. Shutdown Procedure 
Procedure". 
Foilow existing checklist f o r  "Vent and Shutdown 
ATPENDIX B 
SOFTWARE ENTERDATA 
Start  0 
2 Input % 0 - 
f 
A I 
A r r n h  v o c  / , Input  which / vy-/ point want to / 
correct: I 
Store data Input new % 0 1 on,disk / , 2 /  + I t  
100 
101 
102 
IO?  
110 
i l l  
112 
113 
120 
130 
140 
150 
! 00 
170 
180 
190 
200 
21 0 
30 0 
31 0 
320 
330 
340 
350 
360 
370 
380 
390 
40 0 
41 0 
4 20 
430 
3 
I = I + 1  
IF I > ! S O  T H E N  GOTO 1 1 1  
IF I ? 100 T H E N  GOTO 113 
GOTO 40 
GOTO 40 
GOTO 40 
REM CORRECT DATA 
I N P U T  'DO YOU WISH T O  CORRECT DATA CY OR N> " ;A% 
IF Mi > 'Y' T H M  GOTO 300 
I N P U T  ' M T A  PO!NT? " ; I  
P R I h T  ' P O I  ' ; l o 0  - Y P C ! ) :  P R I N T  
INPlJT 'NEW X 02 " ; P O  
GOTO 150 
REM WRITE DATA T O  D I S K  
I N P U T  'F!LE NWE ';FS 
P R I M  GB;'DELETE';RS 
P R I N T  D%;'OPEN" ;FS 
P R I N T  DS; 'WRITE ' ; f ?B  
P R I N T  N P  
FOR I = 0 T O  NP - 1 
P R I N T  X P < I >  : P R I N T  Y P ( I >  
NEXT I 
P R I K T  D%; 'CLOSE" ; R 3  
P R I M  DS; 'LOCK' ; F S  
END 
Tfl = I + 12.33 / 60 
Tt l  = Ttl + 49.32 i 6 0  
R1 = Ttl + 24.66 / 60 
N P  = I 
Y P ( 1 )  = 100  - PO: P R I N T  : P R I N T  ' Y P ( ' ; I ; " >  = ' ; Y P ( I > :  P R I N T  
!B = C H B  ( 4 )  
P R I N T  Da; 'OPU4' ;FS 
?' 
.i; 
APPENDIX C 
SOFTWARE P LOTDATA 
Start 0 
I n p u t  pressure 
Input t i m e  
n p u t  f i le n a m e  
I 
Read data 
from disk 
r - l  Set up axis 
1 Plot the data 1 

ORIGINAL PAGE 1s 
30  y' = 8 
::;I> "3R y = y t  1 0  y 2  ':-TE" y 3  
-. 4 7 :-# _._. I '  INT fYJ / YL) = Y 4  / Yl. THE:.; 3 f 7 0  
' ? ! z ,o  FPIrgT Ts:,'z;"TL ; F & , " : . . c t "  " ' a ' " .  IT;": l>OTO 21:s:) 
1 -9 pp 1 iT T t  ; 6 ; " T L  1 ; ''YO * i 'I j * pt . ; 7 - 4  . .f , - . 3 ; "'f 1 'gym ; Fc; * , n - ( *  ; * 9 -  
FD;" 
> e n  
,100 Y 4  = Y 4  + 1 
? i 30 . ,  
22C-o F~'I:JT TE:,E;"D!-I;P&" :'.IT - I . -  q.2 - "1 j .,' l i !  i " , "  IhlT C(1 + cy2 - )'I - 
I .  
) ,,' 3 ) "  ; ~ ~ i C t ,  1 ; t B " Y % "  i n  
2210 FEIr-tT T3;ZS;"FU;PA" I N T  ( Y !  + {IC? - . X l >  / l C I > ' , '  !NT (Y2>';OII,O; L 
B " T I  0' ; . 
sx:x3 = x3 / SX:YO = YO / SY:Yl = Y l  / SY:YZ = Y 2  / SY:Y3 = Y 3  / SY 
2220 PRINT D S ; " P i ? # O ' :  FEINT fS;'IN#O':XO = XO ./ S X : X l  = Y l  / SX:X2 = X 2  / 
2 2 3 0  PETURN -- 79.10 REM TO PLOT ON GRAPH PGFER CHANGE L I N E  2040 TO IF1150,960,?150,6?6 
2 5 0 0  REM SUBROUTINE PLOT DATA ( I IE) 
2510 REM MUST FOLLW A PLOT AXES ROUTINE. TO PLOT W GRAPH PAPER C W  
2 5 2 0  PRINT DO;'PR#O': PRINT W;"!NltO.: !NP!JT 'C!-!!XSE CYHEOL 
2530 TQ = 'WT%':Dg = CHRS ( 4 ) : Z O  = CHRQ (26) 
2540 X 1  = X 1  * SX:X2 5 X2 * SX:X3 = X 3  * SX:Yl = Y !  * SY:Y? = Y 2  *. SY:Y3 = 
2 5 5 0  F R I N T  DS ; 'PR#3' : PRINT TO ;ZS ; ' I N  ; 1 P1328,lOOO ,9328,6760 ; SC'X1 , 'X2' 
3 5 6 0  P R I M  T3 ;Zg ; 'S I  .2, .2 ;D I  ;. 
2570 FOR I = 0 T O  NP - 1 
2 5 8 0  X = INT (SX * X P ( 1 ) ) : Y  = INT (SY * Y P ( I > )  
2500 
2 6 0 0  NaCT I 
2 6 1 0  PRINT DQ;'PR#O': PRINT DS; ' IN#O":XO = XO / SX:X1 = X 1  / SX:X2 = X2 / 
2020 RETURN 
3000 REM SUBROUTINE TO PLOT MORE DATA 
3 0 2 L  TS = 'WX' :D% = CHRQ ( 4 )  :ZO = C H P S  (26) 
0 
- 
NGE L I N E  2550 TO I P1150,  ?do, 91 5 0 , 6 ? 6 0 .  
Y 3  * SY:XO = xo * SX:YO = YO * SY 
, " Y l ' , - Y 2 ' ; F u ; "  
PR I NT TS ; 2 %  ; . Sn' SPg ' ; PA 'X , . Y ' ; Sn ; ' 
SX:X3 = x3 / SX:YO = YO / SY:Y1 = Y l  / SY:YZ = . Y 2  4,' S Y : Y 3  = Y 3  / SY 
3010 S I %  = . , ,. + !?s 
3030 X 1  = X1 * SX:X2 = X 2  * SX:U3 = X 3  * SX:Yl  = Y l  * SY:Y2 = Y 2  * SY:Y3 = 
3040 r"RIt4T G%;'PI?#3.: PRINT T ~ ; Z ~ ; ' I N ; 1 P 1 3 2 8 , 1 0 0 D , 9 ~ ~ 8 , 6 7 e O ; S C m X l ~ , ~ X ~ D ,  
3 0 5 0  PRINT TS;ZO;'PU;PA' INT ( X 1  + ( X 2 ' -  X1)  / 10 + !J * 6 * S X ) ) . , '  INT . 
3060 P R I N T  DS;'PR#O': PRINT DO;'IN#O':XO = XO / SX:Xl  = X1 / SX:X2 = X2 / 
3070 RETUW 
3 
Y 3  * SY:XO = xo * SX:YO = YO * SY 
" Y I ' , ' Y 2 ' ; P A m X 1 ' , . Y O ' ; P D i .  
CY2) . ; DI 1 , 0 ; LB' SI f * ; . 
'sx:x3 = x3 / SX:YO = YO / SY:Y1 = Y1  / SY:Y2 = Y 2  / SY.:Y3 = Y 3  / SY 
APPENDIX D 
SOFTWARE BEST-F I T  
i 
I 
Compute f er ror  
1 
Input  valze T1 
i 
Set up axis 

2040 
20 50 
2060 
2070 
20'JO 
20 ao 
21 00 
21 10 
21 20 
21 30 
2i  40 
21 50 
21 60 
21 70 
21 a0 
21PO 
2200 
2210 
2220 
2230 
2240 
2500 
251 0 
2520 
2530 
2540 
2550 
2620 
I 
APPENDIX E 
SOFTWARE MINIMUM T2 
t 
Print data 
3 
Input starting depth 1 Input value T1 
I Read data from disk I 
/ input Starting: TZ 
/ First point want to fit 
r:- ? -  L ? -  _ I  -1 
/ / r i i i t ~ i i i i i y !  I L  
- .  
Increment T2 
Compute theoret 
vaI& I mole of Nz 
I Calculate the I 
I s um of Tz 
f No 
I @I ST 
f 
10 REM PROGRMl T O  COMPUTE THE MINIMUM VALUE OF T2 :MT2 
20 DIM x P ( 5 0 0 )  ,YPiSOO) , Y T ( 2 0 0 )  
30 INPUT 'STARTING DEPTH ZO/* ';zO 
40 ARG = ABS (ZO) 
50 GOSUB 1050 :  REM COMPUTE ERF 
60 = . 5  + ( 1  - R F  * SGN ( z o ) )  
7 0  PRINT ' M .  MOLE VALUE = ';xN 
ao INPUT ' W L U E  O F  TAUl -  ' ; T l  
90 REM READ DATA FROM DISK 
100  0% = CHRS ( 4 )  
110  INPUT ' F I L E  W E  ';= 
120 PRINT 0 9 ; ' O P E " ; ~  
1 2 2  PRINT D%;'READ';RI 
1 2 4  INPUT NP 
1 2 6  FOR I = 0 TO NP - 1 
1 2 8  INPUT XPCI): INPUT Y P C I )  
1 3 0  NEXT 1 
1 5 0  PRINT ~ ; S C L ~ S E ' ; ~  . 
155 REM FIT DATA 
1 6 0  INPUT 'STARTING T2= -;TS 
170 INPUT ' F I N I S H I N G  T2= ';TF 
180 INPUT 'STEP T2= ';TC 
1 9 0  INPUT 'F IRST POINT WANT TO PLOT= ' ; I 1  
195 PR# 1 : PRINT 'T2' , 'SU.1' : PR# 0 
2 0 0  FOR T2 = TS T O  TF STEP T C  
210 s = 0 
220 FOR I = I 1  T O  NP - 1 
230 REM COMPUTE THEORETICAL VALUE n ( I )  
300 81 EX? ( - X P < I > - /  T I )  
3 1 0  QO = Z0:G = SGN (QO>:ARG = 'ABS (00) 
350 GOSUB 1000:  REM COMPUTE ERF 
360 EO = RF:GO = G 
3 7 0  01 = X P < I )  / T2 + Z 0 : G  = SGN (Q1):ARG = ABS (Q1) 
380 GUSUB 1000: REM COMPUTE ERF 
390 E l  = RF:G1 = G 
4 1 0  GOSUB 1000: REM COMPUTE ERF 
4 2 0  E2 = RF:G2 = G 
4 3 0  Q3 = 23 - T2 / 2 / T!:G 9 SGN (Q3):ARG = ABS ( Q 3 )  
4 4 0  GOSUB 1000: REM COMPUTE ERF 
450 E3 = RF:G3 = G 
460 AX = XP(1 )  / T I  + 2 0  * T2 1 T l  - (T2 / 2 / T 1 )  2 
4 7 0  IF (62 * E2 - 63 * E3> = 0 THEN Ex = ( A 1  / P) * ( - M P  ( - AX - Q2 
4 8 0  IF > 3: 0 THEN = a p  ( - A x )  * ( G 2  * E 2  - 63 * E3): GOTO 5 1 0  
490 LX = - AX + LOG ( G 2  * E2 - G 3  * E3) 
500 M = M P  (UO 
400 Q2 = X P < I )  / T2 + 20 - T2 / 2 /  T 1 : G  SGN ( Q 2 ) : A R G =  ABS (02) 
2) / Q2 + EXP C - AX - Q3 2) / 03): GOTO 510 
5 1 0  ~ ( 1 )  = 
5 2 0  REM WLCULATE THE SUM O F  T 2  
* 81 + ( 1  - GO * €0)  * ( 1  - 81) / 2 - ( G I  * E l  - Go * €0) / 
2 + M / 2:YT(I) = r r < I )  * 100 
530 s = S + (YPCI) - rr(r)) - 2 
540 NEXT r 
550 PR# 1 : PRINT T2,S: PR# 0 
5.50 NEXT T 2  
570 INPUT 'MOTHER FIT ? ( Y  OR N) ' ; F T B  
580 I F  FTS < > 'Y' THEN GOTO 600 
500 GOTO 1 5 5  
600 END 


Support of the eight-foot high temperature tunnel modification project

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