NASA Contractor Report 178080 NASA-CR-178080

19860014150

THERMAL MODELING OF A METALLIC

THERMAL PROTECTION TILE FOR ENTRY VEHICLES

", ~~$ .;'

~, .r - ._~. ~_.. -'

Michael R. Wiese • -"'1

Computer Sciences Corporation

Hampton, Virginia

Contract NASl-17999

April 1986

~J3RARV COPV

APR 29 '986

LANGLEY RESEARCH CENTER

LIBRARY, NASA

HAM?TON, VIRGINIA

NI\SI\

National Aeronautics and

Space Administration

langley Research Center

I-lampton, Vir~linia 23()G~

,
3 1176 01309 0270
r 1~" Tcr'l {'lID \1 ....... t"'1. t ~~~•.~.~ ....

\ DISPLAY

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....-.. f.-... i .r- 1 ",-. protectlon t1!e for "::~::.:.~..... t 'C.=-

~la.

; r- dO. rBeta 1 tilt......

[IO!:\Jr:1EtJT

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SAP:

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IJi'4I TEC! STATES

MAJS~ ·;*COMPUTER PROGRAMS;*OESIGN ANALYSIS/*PREDICTION A~!ALYSIS TECHNIQUES/*

SPAC:E SHiJTTLES./~tTHERt'ilAL PR()TE(:T I c:r\l / , UC/\T tn_nt REUSABLE

SH IELD I!\!G./ .TE!~~lPERAT~JRE DEPEr~iDEr4CE

•

SUMMARY

This paper describes the development and usage of the

The rmal Ene rgy Flow S imula t ion (TEFS) compute r prog ram. The

program's function is to simulate transient heat conduction in

composite solids and accurately predict interfacia~ temperatures.

Development of this program was undertaken in order to

analytically test the thermal characteristics of a proposed

thermal protection tile system for the Space Shuttle Orbi ter •

This tile configuration (referred to as a Shell Tile*) consists

of an outer metallic shell which is filled with multi-layered

flexible insulation. The objective was to determine individual

transient temperatures between layers of dissimilar insulation

materials and to accurately predict the peak temperature of the

underlying thermally protected aluminum structure. A major

assumption was that (along wi th each material layer's thermal

properties) the only known variable is the temperature of the

outer surface.

The therma I protect ion tile system was heat tested and a

time history of the interfacial temperatures was recorded. Using

the TEFS program, a computer simulation was conducted to

analytically determine the temperature distribution. The

computer simulation provided a peak aluminum temperature that was

within 4% of the actual.

*United States patent number 4,456,208 dated June 26, 1984

entitled "Shell Tile Thermal Protection System".

i

TABLE OF CONTENTS

Page

INTRODUCTION ....................... 1

• PROGRAM INPUT/OUTPUT ................... 2

PROGRAM UNITS ...................... 4

ANALYTICAL VS RECORDED DATA ............... 5

THEORETICAL MODELING ................... 17

CONCLUSIONS .................... 19

REFERENCES ........................ 20

iii

INTRODUCTION

A new thermal protection system, referred to as a Shell

Tile, has been proposed for possible application to future entry

vehicles. In order to optimize the tile thickness via an

analytical model, the Thermal Energy Flow Simulation (TEFS)

, computer program was developed. The unique feature of this

program is its ability to accurately simulate the thermal

characteristics of a composite solid when the only data available

are the top surface time dependent temperature and the materials'

thermal properties.

The basis for the TEFS program is the THERMAL RESPONSE

FACTOR (RESFAC) program used in NASA'S ENERGY COST ANALYSIS

PROGRAM (NECAP). In both TEFS and RESFAC, the equation of heat

conduction for unsteady state/linear flow is solved using the

Laplace transformation method. This method was used due to its:

i) Direct application to composite solids.

2) Easy input requirements.

3) Fast computer execution time.

A detailed analysis of the method can be found in references 1

and 2.

Note that the following assumptions govern the use of the

Laplace transformation method as used in TEFS:

i) Heat transfer is by conduction in one dimension.

2) No contact resistance exists between material layers.

3) The composite solid is initial'ly at a uniform

temperature.

4) Values of temperature dependent thermal properties are

determined by the temperature at the top of the

respective material layer.

5) The last layer of the composite solid is either an air

or vacuum gap which is held constant at the initial

temperature.

In order to obtain an accurate simulation, the following

criteria should be observed:

i) Thick materials should be subdivided.

2) The last material of the model being analyzed should be

an air/vacuum gap whose only thermal property is a

constant resistance.

• 3) Any material which has negligible thermal mass should

have resistance as its only thermal property.

4) The time step selected for the simulation should

accurately reflect the supply temperature's duration.

5) Temperature dependent thermal properties should be input

such that the temperature range being simulated is

accurately represented.
PROGRAM INPUT/OUTPUT

Two input files are required for the TEFS program. The

first file, accessed under file name MODEL, contains the temperature dependent thermal properties of each material layer comprising the composite solid. File two, accessed under file name

SUPPLY, contains values defining the thermal simulation. Note

that data in both files are free formatted.

The contents of file MODEL are:

Item Description •

N, IU N: integer number of material

layers; maximum of i0

IU: integer units flag

0 for English,

1 for Metric

Ii,I2,...,I N Integer number of temperature

variations in layers

l(top),2,...,N(bottom); maximum

of 20 for each layer; note that

a layer having a constant

resistance must be entered as a

-i

NOTE: Repeat the following for all material layers, proceeding

from top layer to bottom

LABEL a Type of material used in the

ath layer; alphanumeric data

with a maximum of 80 characters

NOTE: The following input is required for each temperature

variation in the ath layer

W,K,D,S,T If layer has thermal mass,

enter real values for:

thickness W, density D,

conductivity K, specific

heat S, temperature T

or

R Layer has no thermal mass,

enter real, value for:

constant resistance R

The contents of file SUPPLY are:

Item Description

DT Real value of time increment

between supply temperature

pulses

2
Item Description

NP Integer value of number of

supply temperature pulses;

maximum of i00

TSI,TS2,...,TSNp NP real values of supply

" temperature pulses from TS

initial through TS end

The output file from TEFS is named SIMUL and contains the

following:

i) Echo of input file MODEL

2) Echo of input file SUPPLY

3) Tabular presentation of simulated temperatures at the

top of each material layer for the number (NP) of time

steps (DT).
PROGRAM UNITS

Depending on the value of the units flag IU, the appropriate

units for the variables in the input files MODEL and SUPPLY and

the output file SIMUL are:

Item English Metric

W ft m

D ib/ft 3 kg/m 3 •

K B tu/h- ft-F W/m-K

S Btu/ib-F W-s/kg-K

T F K

R h-f t2-F/Btu m2-K/W

DT s s

TS F K
ANALYTICAL vs RECORDED DATA

A new design for a thermal protection tile has been

investigated as a possible alternative to the current space

shuttle orbiter tile system or as a heat shield for future

aerospace transports. This new design differs significantly from

, the currently used tiles. Rather then use rigidized ceramic

tiles, the proposed design consists of individual metallic shells

which are filled with layers of low density flexible

• insulation. Figure 1 contains a description of this metallic

shell concept.

Heating experiments have been conducted on this tile design

in order to obtain temperature profiles of the materials'

interface regions. Using program TEFS, an analytical solution

was obtained. The TEFS input files MODEL and SUPPLY are listed

in TABLES I and II respectively; output file SIMUL is presented

in TABLE III. A graphics comparison between recorded and

analytical data is shown in Figures 2 through 7.

The computer simulation, run interactively on a Control Data

Corporation CYBER 160/170 series computer, required 40 CPU

seconds and 73000 (octal) 60-bit words of memory to execute.

Probable causes of the discrepencies between recorded data

and the analytical solution are:

i) Computer simulation is one dimensional heat conduction.

2) Thermal properties are ideal.

3) There is an initial temperature gradient within the

model.

4) Uneven heating rate exists due to staggered pattern of

heating elements.

5) Thermocouple inaccuracies, especially at low temperatures.
_= 15 x !5 cm

/---Upper shell (ceramic coatings)

/ /--Stiffener _) " " " Insulations

/VVVVVV_'/\I\/\/\I\/V\I\I\I\IV\I\I\I\/\IV\IV\I\I\I'

• _ Space

- -- High

Self-locking temperature

mechanism Intermediate

temperature

Lower shell " '

_._---_---.__._ temperature Lower

Composite

fasteners

Structural skin

(or honeycomb sandwich)

Bond/insulator

Figure I. Metallic Shell Tile concept. Numbers refer to

thermcouple locations and also comparisons with

simulated temperatures.

6
TABLE I. INPUT FILE MODEL

7 0

• 17 17 17 17 8 4 -I

TOP RENE

j 0.00042 5.1993 512.0 0.0987 0.0 100.0

0.00042 5.8925 512.0 0. 103 0.0 200.0

0. 00042 6. 5858 512.0 0. 1072 0.0 300.0

0.00042 7.279 512.0 0.1114 0.0 400.0

0.00042 7.972-3 512.0 0. I157 0.0 500.0

0.00042 8.6655 512.0 0. 12 0.0 600.0

0.00042 9.1709 512 .0 0. J"4-""-"_ 0.0 700.[3

0. 00042 9. 676.3 512.0 0. 1285 8.0 800.0

0.00042 10. 182 51 "4_.0 0. 1327 0._ 900.0

0. 00042 10. 687 512• 0 0. 137 0.0 I[_00.0

0. 00042 11. 193 512.0 0. 1412 0.0 110_,,0

0.00042 11.698 51-".-'[_ 0 . I4__:,._ 0._ !20_-_.0

0• 00042 1°_.•203 51 "_'_-• 0 0 . 1.492 0.0 1300.0

0.00042 1_"_..709 512•0 0. 15__1 0.0 1400•C_

0. 0004.2 13. 214 512.0 0. 1549 0.0 1500.

0.00042 13.72 512.0 0. 1577 0.0 1600.[_

0.00042 14.225 512.0 0.1605 0.0 170_.0

"[OF'SHELL QUARTZ INSUL

0. 0625 0. 0108 3.0 0. 18 0.0 10_• 0

0.0625 0.01I.7, 3,0 0._-° 0.0 ?00.0

0. "VJ_!"_ _ .",J= 0 • 0154 3.0 0.°15 .c. 0 - 0 300.0

0. 0625 0. 019 3. _ 0. "23 _. 0 400.0

0• 0625 0. 0227 3.0 0.24 0.0 500.0

[9.06_:u 0 0263 3._:! 0."= 0.0 60[_.0

.0._/_,_j'= .. 0 .03 "5•0 0 •""z._ ..J 0.0 .70_.0

0.06.q5 0. 0337 1. -3.0 0.26 0.0 800 •0

0. _ _._J 0. 0383 3.0 0 26 ..5 0.0 900.0.

0. 0625 0.04.28 -,'0_. 0.27 0.0 J000• 0

0.O/.,__=-.'.,J0.0496 3•['9 0 . _"_-7'=_, 0.0 1 10._., 0

0. 062.5 0. 0564 -.:_'_',. 0.28 0, 0 ]200. _

0.0625 0.0632 3;•0 0 ._'85 _, . 0.0 130,}_.[_-.

0._,625 0•07 3•0 0,'_"7 :,-. 0._,_ _.,_,0[_, o.8

0.0625 0.0788 3.0 0 _,o= .o

0. 0625 0. 0875 3.0 0. "5 0.0 !600. [_

0,,06z,_-,,_..-0. 0963 3.0_ 0 ...:,_._, 0 0 1.7_0 [.) , -

MIDDL.E SHELL QUARTZ INSUL.

0 _._,:'.,J0._108 3.0 0.18 0 0 -

" C.h_,. 5:,.._..., _ [_.I1"7 _. VJ F3 _._ ......

"'_F, [_. 7;(.:!FIZ.2) 0 ,.0/::;25 0•. r_;,,..... _..._-._. , 3 • ILl ' _',_, I [9

0.0 625 0 . {__1.,"",: -3,,IZI 0 ,..-......... F..f!_'i _-..'.::,

" 0.06,-,_, '-'= 0 •0..... ._.:_.'"","5. [_ [_ 24 [_, [3 ..,, =-."_.f3_;_

I.;_.0 6 -"._ ['_• 0.-..6..-, o • 0 (;_. xL _.l (,.t:.[.') 6 (_1(_,,0
TABLE I. (cont.)

0. 0625 0.83 3.0 0. 255 0.0 700.0

0. 0625 0. 03371 3.0 0.26 0.0 800.0 •

0. 0625 0. 0383 3.0 0. 265 8.0 900.0

0.0625 0.0428 3 0 0 27 0.0 1000.0

0- 0625 0. 0496 3.0 0. 275 0.0 1108.0

0. 0625 0. 0564 3.0 0.28 0.0 I-B_00.0

0. 0625 0. 0632 3.0 0. 285 0.8 1300.0

0. 0625 0.07 3.0 0.29 0.0 1400.0

0. 0625 0. 0788 3.0 0. 295 0.0 1500,0

0. 0625 0. 0875 ":,.0 0.3 0.0 _600.0

0' 0625 0. 0963 3.0 0. 305 0.0 1700.0

BOTTOM SHELL QUARTZ INSU!-

0. 0625 0. 0108 3.0 0. 18 0.0 !00.0

0. 0625 0. 0117 3 .0 0. "'_. 0.0 20_. 0

B. 0625 0.8154 3.8 [4.215 0.0 300.0

o.o62 o.o2.-:7 3.0 o. 4 0.0 5oo,o

0. 0625 0. 0263 3.0 B,,25 0.0 608.0

0. 0625 0.03 3.0 0. 255 0.,0 70_. 8

0. 0625 0.03.371 3.0 0 ,,26 0.0 800.0

0. 0625 0.0..-_-,83 P::.8 0. 265 0.0 908.8

0. 0625 0,.84.28 3.0 0.27 0.0 1008. [_

0 ..06_:._, 8 (.." .: (_. "-'5 0 0 ! 1,_¥. 0

0. 0625 0.0 Jc:,,.l 3.0 B. _-[_ 0 (_ 120C'. [,:.i

0. ._J._-"..J _! .-,=. 8 .O:!,.:.....z. 3.0 0. 285 0. (:'9 1.::._C:, "1: 0.

O. 0625 0.07 3.0 0.29 0 ,,r2 1.4r_O(_,0

"_"=; 0.0 .1...,8 = ""_J. _ 0

0. vJ'_u./.._=:._ 0. 8788 3. B 0. _-'T_

0. _J_-_ "_'='_! 0. 087[5 3 ,0 0,3 0.0 !60__),0

0, 0625 0.09'63 3.0 0. 305 8.0 1708.0

NOMEX FFLT (TIF')

0. 0133 8. 0198 5.4 0. 3171 0_ 8 108.0

0. 0 :].33 0.0232 5.4 0 . ._,'_°._. [Z_. 0 _:(0I:.. (_]

0.01375 0 •0_-6._ 5.4 0 - ._',._,...1 0 . 0 30r,_- .0

8.0133 0. 0304 5.4 0, 3.38 0.8 4.0.,0.0

0, 0133 0. 034:; 5.4 0. 342 0, 0 50_. 0

0.0133 0. 039 5.4 0..345 0.0 68E'.0

0. 0133 0 04.3"1- 5-;.4 0. _'= 0.0 7_,1i., (_

0.0133 0. 8478 5. zt 0.36 0. B 8_Z_8._

ALUMINUM S'T[_:LJCTUF:.'.E: CONDUCT ION

0.02 78. (_ 1-":_..,,,,_ 0 _57.025 0, 0 1_ ,...

0 (..:1 - " "

tT_.82 ':;(_.0 ] ,'. ....12'_ _, 22::_, (h, ('_ -_:".+:.I:_, ;

8. ('_'2 9:,'. 2 ] 75. [._ (_,..?:.".;2' _!,,V_ .':1. :'_[:",[:5 .i

_HI_I.I_',.!.l'.l ' I I_, _" l F, "~,r.,,.d..'] ", ".I-",'r," I01"..1"1"0 %'_"I-t,'."'!._L I'_R

Zl6 ,,[_)
TABLE II. INPUT FILE SUPPLY

60.0

28

65.25 186.7 795.1 706.4 1065.8 994.8 1230.0 14-78.4 1614..3

1637.9 1654.9 1663.6 164-7.8 1647.4 1652.6 1658.4 _655.9

1477.6 1293.0 1070.0 915.4 809.7 731.9 670.7 620.8 579.7

544.5 514..6
TABLE III. OUTPUT ["ILl".SIMUL

I

ECI-,O L.r" INF'UT F!LE MODE:.

.......... I"=..[.,._1_. ,,t_l OF:' l_.LI:"F, UT F!LE SUF'F'LY ..............

TIME TEMF'EF,'ATURE AT' TOP OF LAYER

SEC I .-_" 3 4 5 6

0 65.._:=u,12'. , ; 65 ...... .:_,i_9 65..-_,,ZI /.._-:..,. 25_. 65.2".=,_ 65 .._5C_

-, / c,-, &.5, A";'°- 65;. 2'.5_ 65.2[-[_ 6.5.25@

6_ 186,7r_,.r8 I 6_ _ ao, ..... -r _, .... 1.2[.'fl 795 . .!.0@ 795. g'..-.';%" -:,'7. f,7.Z: (5. ."'< (_") r:,_? &5,, ..:,]k. 65 .,::...,.P,

1.8_a 7_.,i.,,. 4et"J 70,'!,. 7:c;t; ! :i:::_i_;1:39 L5.7! 0 65° ?,'f.:,t.-5 65..'7'5.'::'

24(3 1.B6,t..-. Bgg.J 1.Bc_, ' "_..,7,5..2; .,.....7o. .7.;?1 &B ,,";',5,-S '-,5 ,,.7.:,1-I 65...._2'..... ::;',

-....:,D{2,, , 994- . B[.,lE_ 99z:. ,.786 4 _i3 ,.79 ! r---'_ ............... ::'_,,':-)_ 65.87 1 65 '25,?

T.:!;6_ 1'-' .'.-,g;. "" glOgJ 1229, r_,..... o..:, 6c,-I•., 2glZ; ".....1 ' _'.,1'_ 65, c'-...... '-''_, :; &'-.,:-=.'- _,, "'.az+_

42_ 14.-', "c. , 4 t"OL,'I t" 4,"_..-",: -.-'_5....... E.. "....- / . _58 I d,2::, :lf:_q .......... . 67,, Z_77 (:_5 .or,_, '"-'

•18{.8 1614- .3_g I ,5:1.4, ".::.'6- 1. _• 0-'-_,.,",.:.... "....J..:".... _'"- , tL.. ....... L-.:!-,:- 7_. J._"_ ,-,-. 6.'_':3"'" .-. ',.... ?-J

=..,-I._ ."1637.9glC , O 1637 . 8.:-'... '_':: 1.......... '-:.',r.,.0 !8..'_', 47!'! , E4.1 75.74c, ;' 65,, .,":d_:_

' 8,., ,,42 B /./_. B 37 6f,_g} 1654 9_t"#1 1 ./..-.,..:,-.I, 878 13 ..6 ,.'-7:? ,.S_'7,,'-';......

, -, "t 8P."7'.,,."-..'3[.'; }.tZ..._z_":" ;, <" t. E " '-' '

t-,c_,t..., 11,,L_Q,..:,".-." 6g}0 . 1.C;"./,",z..".:, . =, ,,J.",,:jl,fnj , _ ...... ,.:'.' ,(,.-.2 ,, "-."" ,",": "i.1 _ ....

72'E-'_1 .1./:>4."-'. [.']_tZ; l&-q'' , -'"" / b'-,' .,' ":...:'"-q'.:.!."}';5",::" c,,'4,.) ., ,",.. x:.',.:1...... I """' .-t.,...... ?77 :':._c' . 4,:7.,£'

? t

7,,c'".r.,u," 1.647 . 4._ _.,647 "'" " :'_ & :!. E ,'..-_, !. ] E,14 _'' .,:--;"..-... !.-7.S 81 :'.; .... 2 i 1,3

l.o,J._:., 600 _Gt;:, - .,? '=".... 1 ..: "''"' , / ,-..:,, 7'C)'_ 1 _I'1'..•! "......... .._ £!.C; *" .... 2[])? '7[:; ,. Z ,3.:.9

¢'.,.._,:: .:, ., .-,c:.,-, 1..., --; ._ ... ,...,_, ...... -/t.:._:., 1. 4 Iglg'l I 1t,.,...... -* ,

8..:,. S,'.':_'::_ 960 "._t ="=; ._-.._'r:,c:, 75 ' 1.' '::"-; .-517, .'7,. c.;,7 """ :_.j.... 9rZIO 1._.... i!-]:7.7; ,.__a.j 8:97 ,:'_..'_

• 1.-,, ,._. _Ozl9 _,,_==" 7&,4 _ _-'_ 1.I.5 9'6. 65 1 1[8_'_') I 477.61_ 1.47,' _[;[0('' _'_ _:" .... =1..... :

"-' 13._,c_._A_,E" 539 .:774 1._1"}_ 129:2;. _gl_', :I291T,. _1. ,.: i ,_.oc,, .... '-." ......... ._..:'__., 1. I _ 5.7 &th

:I _4[._ I _,?]7_'i.;'_g'_ 1.17_-"_._:,"1 11.:T;:'. 7::'::I_', t-"95, 31.5 ...:,4:_,.I ,.-, . ] ....... :,...:,

:1.i'ti{:_ 9' t 5. .......Zl,_b.'Z.._ '71.5 ,q.:lEl .,d:::, ,, " ;,, ......... !::;!,4 9.".... :!.5.. 7:&:[ :."!.47. c-.-':',= ; ,......, :I.... .::............. " FI7:?

•":' , '-5

_": '-_ ..:.'i {_-, 1

.,::.c.,L. 8gF'7.7[':_'}1 c:.,.,;,,';"1, . .-','. . _,-..:...........

I 7__,;!'_ 7 3:1_ 9' {'_i,3 7 :........ '":'1 '7 1..''..' _'_:,? ,,[':'" ..,..." 7'7171. ,. ":'-.'' ='" .--........ .-;.?.p.-,. / ,'",c', _ .i 4 3 .[[:=:_: . ?

€:- Zl --_,',.

I':_Rr:._ .... L.7t._..71:_r_ 670, ?;['_ ?r.......... n-, .... .,.:..,i_ ,r 771 8-,.c:, .... _ _".: 72zi 1

,-, _._ -_ r", r'_ r."_:", _ ,"7'0 "! r-- {:3 Z _" ,_" I 4 ziI}'+ 621Z;. 8 _",t:._ .:+_. , .....8 i_:.8'_ 71..:::- 6.., :. :2;@3 0{:'1g:

!..... ,=_..... .,{._ ...... -7 o, ..5' _{_,r.,_ =_....; 9.7 _._.} .7 //-..........

:,£ 1 I 7 t-,I:'-.: _ 6U2 '-'('' 1 , z_-, _ ,_-"--; 3 g ,.!:

- ,:, :: ......._.,..g'.i,,::, 54"I. ,,5'P_ ,:._=., ""t ;,"_.,,.-.SF;I :==' 88 _;1 _.,=::- .::; :1." "'""-'"' 1/:T'..F.'_'' ',:.'.

....._(::: B. .....q.-I.,, _: .-""J;_..... :'"_c.:. -

I z _",.' ., ..-'C', ,.. ,, ,-' -._ ,, L%(_ 1 t2_; "'.:,,::,,.'3 5 ] 4.6 _ 8 5 t 4 ,,cS{:'4i = " "_' _f:.C'] 1 .. .............

Note: See figure 1 for locations of temperature simulations.

10
, 3~,O

•

lIlII-

-

-

-

-

.~)

I I

270

I J I I

540

I

I I I I i I I J I I I I I

810 1080

TIME (SECONDS)

-.-----1

I

I

I I I I

11'\20

Figure 2. Supply Temperature to Top of Shell

11
1680 i

- /- _--------_,

1540 -_ ¢

- I!

1400 _

1260 __---- ___\

,. - _,

,.,_ 980_ I_ ., \\ x ....

,., - ,\

n- 840 -- _ "

!-- \,

< - _, .',",,

LI"J _ \\

a. 700 //'',4 \"

,,i I/ _\

I--;

560 ._ ,

-- if DATA I

420_ I THEORY ,

280

140 i '.

t =

o I I I I I I 1 I I I I 1 I I I I t I l I I 1 1

0 270 540 810 1080 1 _50 1620

TIME (SECONDS)

Figure 3. Top of Insulation Pack 1

12
14.16 ,,,..-

1298 / -- q\

- ) /

,_ 1180 _ / /

/ : / \,,,,,

1062 _-- I /I / \_

944 -- I \" '\

- \ \

826 I _.

W "

n,, 708 L'- / 'X,

_) '

I-- t

< : I N.

,,, - / ""-

a. 590

._ _- /

I..d

__ _- i

472 /

354 -- t // DATA THEORY

-- I /

236-- // /

- 7 / 118

o-I I I I I I I I I I I I I I I I I I I I I I I 1

0 270 540 810 1080 1350 1620

TIME (SECONDS)

Figure 4. Top of Insulation Pack 2

13
1116

1023 ( _.

- / \ .

_ / \

930 _ / t

837 --

/

-/ _"_ -

-D / \

: / \

744 l \ "_\

_ / \

LU 651 i X

e. _: / \,

" 55B / \

/

n,

a_ 465

=W

372 _ /

- I

-- / / DATA 279

-- / / THEORY

- ; /

186 _ /

-- /

-- / /

o-i i i I I i I I I I I I i I t I I I I I I I I I

0 270 540 8i0 1080 1350 1620

TIME (SECONDS)

Figure 5. Top of Insulation Pack 3

14
420

-- DATA

385 _ THEORY

350

- /

315 / _\

- / \

-- _ .

280 / _"

u_ _ /

Q

w 245 / /

,,, -- t /

r_D 210 / / --

< - I I

n-

_. 175 _ /

hi

z /

14o /

- / /

105 / .....................

/ I

/I

70 .I-I35 t

o-_ 1 I I I I I I I I I I ! I I I I I I I I I I I

0 270 540 810 1080 1350 1620

TIME (SECONDS)

Figure 6. Top of Felt Pad

15
2O6

b

-- DATA .

180 _ THEORY _' _.

167 " "

154 -

t.=..

o - i ,_

,,, 141 ....

m _ /j

n- 128 ,/

:D __ // "

n,,

r, 1i5

Ld

1.--

102 -------- / "

89 " -

- /4'

76 Q'

-_-

63 .......

50-1111 I I I I i I I i I I I I I I I I I I.I i

0 270 540 8 0 1080 1350 1620

TIME (SECONDS}

Figure 7. Top of Aluminum Structure

16
THEORETICAL MODELING

The results obtained from both the heat chamber test and

computer simulation show that the peak aluminum temperature of

approximately 180 degrees F was well below the allowable maximum

of 350. Since the aluminum temperature is the critical area of

interest, it is desirable to know the optimum insulation thickness-peak aluminum temperature factor. To obtain this, ten

additional computer simulations were conducted, each using a

decreased total insulation thickness (rate of reduction was

0.0095 feet per simulation). The results are presented in Figure

8 as an insulation thickness versus peak aluminum temperature

operating curve.

This optimization run shows that the tile thickness could be

reduced from 2.25 to i.ii inches without exceeding the allowable

350 degrees F structure temperature. Based on the materials used

in the simulation, a 4 tile array which is 2.25 inches thick with

a top surface area of one square foot weighs i.i pounds. The

reduced insulation thickness tile weighs 0.65 pounds, resulting

in a weight reduction of about 40%.

17
360

4.

350.

340

330

"-" 320

m

6 310

ot

= 300 "o

uJ 290

n,,.

:::)

p. 280

<

'_" 270 IJ.I

n

•_ 260

I.l.I

250

m 240

_z

"_ 230 --

::)

_1

.<: 220

v 210

'< ..

,', 200

190

180

170

160 I I I I I I I I I I

1. 1 1.22 1.34 1.45 1.57 1.68 1.79 1.91 2.02 2.14. 2.25

TOTAL INSULATION THICKNESS inches

Figure 8. Theoretical Operating Curve

18
CONCLUSIONS

Within the framework of the governing assumptions, TEFS will o

provide a fast, low cost, accurate simulation of transient heat

flow in a composite solid. As a aid in model design, TEFS

enables a multitude of configurations to be analyzed in a short

period of time, thus significantly reducing actual constrUction

and testing costs.

19
REFERENCES

i. Wiese, Michael R.; NECAP 4.1 - NASA's Energy Cost Analysis

Program - Thermal Response Factor Routine. NASA CR-165982,

August 1982.

2. Wiese, Michael R.; An Analysis of Thermal Response Factors &

How to Reduce Their Computational Time Requirement. NASA CR165992, August 1982.

L

3. Carslaw, H. S.; and Jaegar, J. C.: Conduction of Heat in

Solids. Second ed. Oxford at the Clarendon Press, 1959,

pp. 109-112, 298-304, 326, 399-401.

4. Carslaw, H. S.; and Jaegar, J.C.: Operational Methods in

Applied Mathematics. Oxford at the Clarendon Press,

1941, pp. 28-32, 53-58.

20

Thermal Modeling of a Metallic Thermal Protection Tile

for Entry Vehicles

(' AepOitNo:

NASA CR-178080

4. Title and Subtitle' .

2. Government AccessIon No. I 3; Recipienrs Catalog No.

.' 5. Repon Date

April 1986

6. Performing Organization Code

7. Authorls)

Michael R. Wiese

9. I'ertorming Organization Name and Address

Computer Sciences Corporation

Hampton, Virginia 23666

.

8. Performing Organization .Report· No.

10; Work Unit No.

11. Contract or Grant No.

NASI-17999

12. Sponsoring Agency Name and Address

National Aeronautics and Space Administration

W~shington, DC 20546-0001

5~' SUpplementary Notes

Langl~y Technical Monitor: Ian O. MacConochie

11>' f-bstract

13. Type of Repon and Period Covered

Contractor Reoort

14. Sponsoring Agency Code

506-40-11-05

Tqe Thermal Energy Flow Simulation (TEFS) computer program was developed to simulate

transient heat transfer through composite solids and predict interfacial

tempera~ures. This paper describes the program and its us~ge.

A sim~lation of tne thermal response of a new thermal protection tile design for

the Space Shuttle Orbiter is presented and g~~phically compared with actual data.

An example is also provided which shows the program's usage as a design tool for

theoretical models.

17. Key Words (Suggested by Author(s))

Thermal Responsi Factors

Transient Heat Flow

Computer Program

Space Shuttle Orbiter

Thermal Protection Tile

18. Distribution Statement

Unclassified-Unlimited

Subject Category 18

19. Security Classif. lof this report)

Unclassified

20. Security Classif. lof this page)

Unclassified

21. No. of Pages

24

22. Price"

A02

N-305 For sale by the National Technical. Information Service, Springfield, Virginia 22161

3 1176 01309 0270