AD755361 1\ \ \\1 III 111\ 11\1111111\111' I.' I 'I, i. i J, Ii: , . A AFAPL-TR-72-55 PRELIMINARY INVESTIGATION OF FUEL TANK ULLAGE REACTIONS DURING HORIZONTAL GUNFIRE R. G. CLODFELTER. E. E: OTT, CAPTAIN, USAF TECHNICAL REPORT AFAPL-TR-72-55 , ," ,I' NOVEMBER 1972 , Approved for public release; distribution unlimited.·--- ,.- : --'. . .,..- ... - ,,".-" ., " , .J "! :' J " AIR FORCE AERO PROPULSION LABORATORY AIR FORCE SYSTEMS COMMAND WRIGHT-PATrERSON AIR FORCE BASE, OHIO u,s. National Technical InTormation Service Springfield, Virginia 22161
Transcript
AD7553611\ \ \\1 III 111\ 11\1111111\111'
I.'I
'I,
i.i
J,Ii:, .
A~~
~
.~
~~~~
~~
AFAPL-TR-72-55
PRELIMINARY INVESTIGATION OF FUEL TANK ULLAGEREACTIONS DURING HORIZONTAL GUNFIRE
R. G. CLODFELTER.
E. E: OTT, CAPTAIN, USAF
TECHNICAL REPORT AFAPL-TR-72-55
,,"
,I'
NOVEMBER 1972
~ ,
Approved for public release; distribution unlimited.·--- ,.-
:--'. ~ . .,..- ".-~- -~_... - ,,".-"
.,", .J
" !:'
J "
AIR FORCE AERO PROPULSION LABORATORYAIR FORCE SYSTEMS COMMAND
WRIGHT-PATrERSON AIR FORCE BASE, OHIO
u,s. D:~=~~~~~~~:~:merceK!§National Technical InTormation Service
Springfield, Virginia 22161
WillIe Secl1~n .:*.:===e~ll S~cllW 0
o
NOTICE
When Government drawings, specifications, or other data are used for any purpose
other than in connection with a definitely related Government procurement operation,
the United States Government thereby incurs no responsibility nor any obligation
whatsoever; and the fact that the government may have formulated, furnished, or In
any way supplied the said drawings, specifications, or other data, is not to be regarded
by implication or otherwise as in any manner licensing the holder or any other person
or corporation, or conveying any rights or permission to manufacture, use, or sell any
patented invention that may in any way be related thereto.
I ••••• •••• U •• ,··············· .. •...............
Copies of this report should not be returned unless return is required by security
considerations, contractual obligations, or notice on a specific docwnent.
AI R FORCEj56780j6 February 1973 - 350
UNC LASSIFIEDSecurity Classification
DOCUMENT CONTROL DATA· R&D(Security dasslflcation 01 rltle, body 01 abstract and Inde1C;ng annotation must be entered when the overall report Is classified)
I. ORIGINATING ACTIVITY (Corporete author) 28. REPORT SECURITY CLASSIFICATION
Air Force Aero Propulsion LaboratoryUNC I:ASSIFIE D
Wright-Patterson Air Force Base, Ohio 45433 2b.GROl,JP
3. REPORT TITLE
PRELIMINARY INVESTIGATION OF FUEL TANK ULLAGE REACTIONS DURINGHORIZONTAL GUNFmE
4. OESCRIPTIVE NOTES (Type of report and Inclusive dates)
Final Technical Report, 1 December 70 to 30 June 19725. AU THO RIS) (First neme. middle InlUal, lsst name)
R. G. ClodfelterE. E. Ott, Captain, USAF
8. REPORT CATE7e. T?o'ljiAGES I'b. NO. 0; RE F"SNovember 1972
8a. CONTRACT OR GRANT NO. 9S. ORIGINATOR'S REPORT NUMBER(S)
b. PROJEC T NO. 3048 AFAPL-TR-72-55
e. Task No. 304807 9b. OTHER REPORT NO(S) (Any other numbers that may be assignedthis repor')
d.
'0, DISTRIBUTION STATEMENT
Approved for public release; distribution unlimited.
II. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY
( '. ~ir Force Aero Propulsion Laboratory\i~ .-r Wright-Patterson Air Force Base, OH. 45433
'> I ,~.' ,r: .l3, ABSTR'AC T
I~ftis'report deals with the effect horizontal gunfire has on the flammability of hydrocarbonturbine fuel in aircraft fuel tanks. Two fuels, JP-4 and JP-8 were used in the testing. Thefuels were placed in an explosion proof test vessel and subjected to CAL. 50 (Armor-Piercing !ricmdiaryf' gunfire. A wide range of conditions were investigated and the resultsare presented. The test program was designed to briefly explore the many facets of thefuel tank fire and explosion problem with the intent of investigating in more detail duringfuture testing;those areas which appear to be of major significance<\.- )...f~
PRELIMINARY INVESTIGATION OF FUEL TANK ULLAGEREACTIONS DURING HORIZONTAL GUNFIRE
R. G. CLODFELTERE.E. OTT, CAPTAIN, USAF'
".......... '. - ......
Approved for public release; distribution unlimited.
AFAPL-TR-72-55
FOREWORD
This report was prepared by R. G. Clodfelter and Capt E. E. Ott of the
Fire Protection Branch, Fuels and Lubrication Division, Air Force Aero Pro
pulsion Laboratory (AFAPL/SFH). The work reported herein was accomplished
illlder Project 3048, "Fuels, Lubrication and Fire Protection, " Task 304807,
"Aerospace Vehicle Fire Protection. "
This report covers research accomplished from December 1970 through
June 1972.
The author wishes to aclmowledge with appreciation the valuable assistance
and contribution of the follOWing individuals: Mr. W. Cannon, Systems Research
Laboratories, for assisting with the data analysis and Mr. S. Shook, Mr. R. Lillie
and Mr. D. Tolle of the Fire Protection Branch for their efforts in data reduction.
Special thanks is given to Mr. D. Foster and Mr. W. Hall of the Air Force
Aero Propulsion Laboratory for their assistance in the performance of the test
program. Use of the Air Force Flight Dynamic Laboratory Ballistic Impact
Test Facility was also appreciated.
This report was submitted by the authors Jillle 1972.
This technical report has be.en reviewed and is approved.
&4.'~/J R. ~~-v-__./I
, CHARLES R. HUDSONChief, Fuels and Lubrication Division
ii
AFAPL-TR-72-55
TABLE OF CONTENTS
SECTION
I INTRODUCTION
II APPARATUS USED.IN HORIZONTAL TESTS
1. Standard Test
2. Externally Connected Tank Test
3. Compartmented Tank Test
4. Fuel Level "Test
5. Entrance Plate Test
6. Exit Dry Bay Test
III PROCEDURES USED IN HORIZONTAL TESTS·
IV TEST RESULTS FOR HORIZONTAL SHOTS
V DISCUSSION OF TEST RESULTS
1. Standard Test
Regression Equations for the Standard Test Results
2. Externally Connected"Tank
3. Compartmented Tank Test
4. Fuel Level Test
5. Entrance Plate Test
6. Exit Dry Bay Test
7. Combination and Special Test
VI CONCLUSIONS AND RECOMMENDATIONS
APPENDIX I TABLES
APPENDIX IT DETERMINATION OF INFLUENCEOF INITIAL ULLAGE CONDITIONSUPON PEAK REACTION PRESSURE
APPENDIX III REGRESSION ANALYSIS
PAGE
1
3
3
5
5
11
11
11
13
14
16
16
19
24
24
33
37
40
40
44
47
58
61
vPreceding page b\ank
l
AFAPL-TR-72-55
LIST OF ILLUSTRATraNS
FIGURE PAGE
1. Tank Configuration (Plan View) 4
2, "J" Tank in Standard Test Configuration 6
3. Entrance Plate Configurations 7
4, Exit Plate of Standard Test 8
5, Bullet Trajectory Through Test Tank 9
6. Perforated Plate of Compartmented Tank Test 10
7. Exit Dry Bay Extens ion 12
8. Measured Parameters 15
9. Overpressure for Standard Test with AtmosphericInitial Ullage Pressure 17
10. Overpressure for Standard Test with JP-4 at 30PSIInitial Ullage Pressure 18
11. Times-to-Peak Overpressure for Standard Test withAtmospheric Initial Ullage Pressure 20
12. Times-to-Peak Reaction Pressure for JP-8 Fuelat One Atmosphere Initial Ullage Pressure(From AFAPL-TR-70-65) 21
13. Regression Equations for the Standard Test Results 23
14. Overpressure Comparison for Standard Testand Externally Connected Tank Test 25
15. Overpressure Ratios Using JP-4(Compartmented Tank Test) 27
16. Overpressure Ratios Using JP-8 (Compartmented Tank Test) 28
17. Overpressure Ratios Using Propane(Compartmented Tank Test) 29
18. Connected Tank to Main Tank Overpressure Ratio 32
19. Overpressure Ratio for Various Fuel Levels 34
vi~"., ....:-. ," -. '". :- "','-
,',' . "
AFAPL-TR-72-55
LIST OF ILLUSTRATIONS (CONTD)
FIGURE PAGE
20.
21.
22.
TABLE
I
II
III
IV
v
VI
VII
VIII
IX
Time to 6pM for Various Fuel Levels (Lean Reactions)
Entrance Plate Test Results
Overpressure Ratio for Exit Dry Bay Testwith JP-4
LIST OF TABLES
Standard Test
Externally Connected Tank Test
Compartmented Tank Test Using JP-4
Compartmented Tank Test Using JP-8, .118°FFlash Point
Compartmented Tank Test Using Propane·
Fuel Level Test
Entrance Plate Test
Exit Dry Bay Test
Combination and Special Test
vii
36
38
41
PAGE
48
50
51
52
53
54
55
56
57
AFAPL-TR-72-55
SECTION I
INTRODUCTION
A one month test effort was conducted to explore the fire and explosion
response of the ullage space of a fueltank when subjected to CAL. 50 Armor
Piercing Incindiary (API) horizontal gunfire. A short test period was established
due to the limited availability of the gun range at Wright-Patterson Air FOI:ce
Base. The test plan was designed to be broad in scope since it was based on
the general opinion that the response of a vapor reaction was somewhat predic
table and any unique facets of the fuel tank ullage fire and explosion problem
could be investigated in detail more effectively at a later time if a broad base
existed.
For the foregoing reasons the following six. test types were selected for
exploration:
1. Standard Test
2. Externally Connected Tank Test
3. Compartmented Tank Test
4. Fuel Level Test
5. Entrance Plate Test
6. Exit Dry Bay Test
The Standard Test was so termed because each of the other five "types" can
be considered a modification of the Standard Test. The influence of these
modifications were then determined by comparison with the results of the
Standard Test.
The Standard Test consisted of firing into the ullage of an uncompartmented·
tank containing only a nominal amount of liquid fuel (4.4% by volume). For the
Externally Connected Tank Test a second fuel tank was connected to the standard
1
AFAPL-TR-72-55
tank by a flexible hose to simulate an aircraft fuel system with interconnected
tanks. The Compartmented Tank Test was performed by adding an extension to
the standard tank and separating the two by a perforated wall. In the Fuel Level
Test the bullet trajectory was held fixed while the amount of fuel within the
standard tank was increased so that the liquid vapor interface approached the
projectile trajectory. The entrance plate on the standard tank was changed in
diameter and thickness to meet the requirements of the Entrance Plate Test.
Both the Fuel Level and Entrance Plate Tests were included to assess the in
fluence these items would have on the transfer of energy from the projectile to
the liquid and the possible ·generation of fuel spray in the ullage. The Exit Dry
Bay Test was designed to determine if a projectile traveling through the ullage
of a fuel tank could generate an external fire on the exit side of a fuel tank. In
these tests, a closed dry bay was attached to the exit side of the standard tank•
. For each of these six test types numerous shots were made at various
temperatures, pressures, and fuel types. In addition to the basic six test types,
a short series of "Combination & Special" shots was made to explore nonequibrium
conditions and other unique facts.
Some of the results of this test program were predictable and other results
were not as expected. The general conclusion of the program was that additional
investigation is required to explain some of the results, particularly for inter
connected tanks.
2
AFAPL-TR-72-55
SECTION II
APPARATUS USED IN HORIZONTAL TESTS
A cylindrical stainless steel tank which could be modified as shown in
Figure 1 was used in this test program. The tank, called a TTJTT Tank, included
pressure and temperature measuring equipment which was added during a pre
vious program dealing with vertical gunfire testing. This equipment consisted
of three thermocouples for monitoring the preignition temperatures of the tank
ullage, tank interior wall, and fuel. Two pressure transducers were used to
measure reaction overpressures. Whenever a tank extension was used one
transducer was located in the main tank body and the other in the extension.
When no extension was used both transducers were mounted in the main tank
/body. All tests used an exit plate 19 1/4 inches in diameter.
Film coverage was made of all shots. The exterior of the tank was photo
graphed normally at 64 frames per second and the interior at approximately
6400 frames per second. During most tests the interior camera viewed the
main tank body. However, in the Externally Connected Tank Test and the Com
partmented Tank Test the interior camera saw only the extended portion. The
TTJTT tank was used in all tests. It was mounted sllch that the planes of the en
trance and exit plates were vertical. The CAL. 50 API projectile was fired
horizontally from a gun mounted about 25 feet away from the tank. All tests
were conducted with a projectile velocity of approximately 2850 Ft/second.
The bullet was aimed such that it passed through the center of the tank. A
closed circuit fuel spray and circulation system was installed within the tank so
that equilibrium vapor concentration could be obtained. Aluminum 2024T4
entrance and exit plates were used in all tests.
~ Specific apparatus and configuration used in each of the six test types was'
as follows:
1. Standard Test
The first series of horizontal shots were the Standard Test.
3
AFAPL-TR-72-55
Q. STANDARD TEST
10
ENTRANCEPLATE~
c. EXTERNALLY CONNECTEDTANKS TEST
EXIT PLATE
b. EXIT DRY BAY TEST
DRY BAY
d. COMPART~ENTED TANK TEST
SOLIDDIVIDERPLATE
Figure 1.
___ ULLAGECONNECTINGLINE
Tank Configuration (Plan View)
4
__ PERFORATEDDIVIDERPLATE
AFAPL-TR-72-55
The test conditions consisted of the following parameter values:
a. The "J" tank in its unextended configuration had a volume of 90 gallons.
(See Figures 1a and 2),
b. An 8 inch diameter, 0.125 inch thick entrance plate (See Figure 3a),
c. A 19 1/4 inch diameter exit plate; the thickness was varied to withstand
the expected overpressure (See Figure 4).
d. An 8 inch bullet trajectory height above the liquid surface; this cor
responded to i 1/2 inch maximum fuel depth and 4 gallons (See Figure 5).
2. Externally Connected Tank Test
These tests were conducted using the "J" Tank with an extension added to
one end as shown in Figure Ie. The extension was separated from the mam
tank body by a 1/4 inch thick aluminum plate. The ullages of the tanks were
connected by a linch diameter hose. The length of the connecting path was
approximately 2 feet. A fuel spray/etrculation nozzle was installed within the
extension tank in order that equilibrium vapor conditions would be formed in
both tanks. In this configuration the main tank volume was approximately
80 gallons with the extension tank volume of approximately 55 gallons.
3. Compartmented Tank Test
The compartmented tank was formed by adding an extension to the "J" Tank
as illustrated in Figure 1d.The 1/4 inch aluminum plate which divided the ex
tension from the main body was perforated by four one inch diameter holes
located near the top (See Figure 6). Several small holes at the bottom of the
plate allowed the fuel level to equalize between the two compartments. The'
volume of these compartments was the same as the externally connected tanks
previously discussed. A fuel spray/circulation nozzle was also included in, the
extended portion to insure equilibrium fuel vapor conditions.
- ,--"'"
5
AFAPL-TR-72-55
Qo....~
~~....'Eo
C)
6
---~-
.-~--
-.
11~r-
RE
TA
ININ
GR
ING
RE
TA
ININ
GRING~
...,r a"
IIII
I\
L19
!."
4
qfj
EN
TR
AN
CJ
PL
AT
E
EN
TRA
NC
E-
PL
AT
E
> ~ "d t"' I ,...:j~ I ..., ~ I tI
ltI
l
o.a"
EN
TR
AN
CE
PL
AT
E
Fig
ure
3.
En
tran
ceP
late
Co
nfi
gu
rati
on
s
b.1
9f'
EN
TR
AN
CE
PL
AT
E
AFAPL-TR-72-55
8
r--I Reproduced from: best available copy.
AFAPL-TR-72-55
TRAJECTORY HEIGHTABOVE LIQUID
MAXIMUM DEPTHOF FUEL
Figure 5. Bullet Trajectory Through Test Tank
9
AFAPL-TR-72-55
10
"
-~ ,.
iI
AFAPL-TR-72-55
4. Fuel Level Test
To investigate the effect of the projectile passage over the liquid-vapor
interface and the possible generation offuel spray, the test tank was returned
to the standard configuration and the amount of fuel within the tank was varied.
It was believed that the massive flange to which the 8 inch entrance plate was
fastened would absorb the energy transmitted to the entrance plate during pene
tration. Thus, any difference in the results of these tests would be due to the
influence of the projectile's passage over the liquid and not its energy lost during
penetration.
5. Entrance Plate. Test
The objective of these tests was to, impart different amounts of energy from
the projectile to the fu~l during penetration. This was done by replacing the. '
8 inch entrance plate with a 19 1/4' inch diameter plate as shown in Figure 3b.
The thickness of the new plate was afso varied at three levels, 0.060, 0.125 and
0.250 inch•. The amount of fuel in contact with the entrance plate was changed
by adding different amounts of fuel to the tank.
6. Exit Dry Bay Test
A dry bay was added to the standard IIJII Tank by sandwiching a small ex
tension between two exit plates as shown in Figure lb. The extension was
19 1/4 inches in diameter and 4 inches in length (see Figure 7). Its volume was
4.8 gallons. The exit plates used were 0.090 inch in thickness.
11
AFAPL-TR-72-55
" '
, ' ,
'/f!
Figure 7. Exit Dry Bay Extension
Reproduced from:'>"best available copy.
12
AFAPL:...TR-72-55
SECTION III
PROCEDURES USED IN HORIZONTAL TESTS
The desired fuel/ullage temperatures were produced by heating the fuel. , i
before placing it in the tank and heating th~ tank by blowing hot air around it.
Equilibrium fuel vapor concentrations were obtained by the following pro
cedure: After the entrance and exit plates were installed the tank was evacu
ated to less than 5 psia. The vacuum lines were closed and the fuel pumped
into the tank. The fuel was circulated through the spray system for at least
5 minutes at the below atmospheric pressure. The ullage pressure was then
increased to the desired test value and the fuel spray-circulation continued for
another 5 minutes. The shot was fired approximately 2 minutes after the spray
was stopped.
In all tests the temperatures of the ullage and fuel were nearly equal.
Also, in all but four special tests which are appropriately identified in the
test results section, equilibrium fuel vapor concentrations were achieved.
13
AFAPL-TR-72-55
SECTION IV
TEST RESULTS FOR HORIZONTAL SHOTS
A total of 130 tests were conducted. The individual test conditions and
results of these tests are given in Appendix I. The following abbreviations
are used in the tables gathered in this appendix.
TL
TU
TW
DE
X·E
DF
HTF -
PI
F/A -
6PM
6™
6PC
6TC
oPc -
Temperature of fuel, OF
Temperature of ullage, of
Temperature of tank wall, OF
Diameter of entrance plate, inch
Thickness of entrance plate, inch
Maximum fuel depth, inch
Height of bullet trajectory above liquid, inch
Initial ullage pressure, PSIA
Fuel. to air mass ratio (Based on British Petroleum Institutemethod of vapor pressure and mass estimation usingdistillation data)
Peak overpressure in main tank body, PSI
Time that 6 PM was measured, seconds
Peak overpressure in extended tank section, PSI
Approximate time that 6PC was measured, seconds
Overpressure in extended tank section at time ignition occurredin that section, PSI
Figure 8 will help the reader understand the definitions more easily.
14
AFAPL-TR-72-55
PRESSURE INMAIN TANK
<[
iiiQ.
IWa:::JIf)If)wa:Q.
-*'-----1
JPRESSURE IN
,....------1---------------1 EXTENDED TANK/" ,
I I 'I I ",
I I "I "
,....----I--~--------~-~ \\ ,
\I II II I
/ I/ II I
" I" II I
/ II I
" II I/ I/ I
/ I---;/ I
aPe -_..... I~---o-L-----._ PI --t""E;i:.:=~--------+_..;.I---------
o TEST TIME-SEC. I I+ 6TM6TC
PROJECTILEPENETRATEDENTRANCEPLATE
Figure 8. Measured Parameters
15
AFAPL-TR-72-55
SECTION V
DISCUSSION OF TEST RESULTS
1. Standard Test (Figure 1a and Table I)
In Figures 9 and 10 the reaction overpressures are plotted as a function of
initial temperature for JP-4 and JP-8 at atmospheric initial pressure and
JP-4 at 30 psia. Two important characteristics of the data are immediately
apparent. Fir,st! t.here is a fuel rich flammabilitY temperature limit for the
JP-4. At atmospheric pressure this limit is in the 51°F to 59°F region and at
30 psia it is between 89°F and 101°F. The standard lean and rich flammability
limits as determined by laboratory experimentation are shown on these figures
for comparison. The other important observation which applies to JP-8 is that
the ullage is ignitable at temperatures well below the flash point (105°F) and the
resulting overpressure decreases with decreasing temperature.
To understand these observations one must consider the ullage composition
environment. First, the ullage contains an equilibrium fuel vapor concentration.
The magnitude of this concentration is dependent upon the volatility of the fuel.
Fuel volatility is, in turn, dependent upon its chemical composition and its
temperature. Increasing the fuel temperature will increase the equilibrium
vapor concentration. Second, the ullage is in contact with the liquid fuel sur
face. In gunfire tests, additional fuel in the form of vapor or spray may enter
the ullage from the liquid surface. The additional fuel could be generated by
impact of the projectile and/or evaporation du~ to incendiary burning or initial
fuel combustion. It is this additional fuel that causes the complicated results
seen during gunfire.
In shooting fuel tank ullages which contain rich equilibrium vapor concen
trations the only effect of additional fuel is to make the ullage more fuel rich.
Thus, it was expected that rich limits would be found for gunfire tests. The
only exception to this would be when the fuel tank is ruptured, due to the pro
jectile, in such a way that air is ingested causing the fuel/air ratio to decrease.
16
100
•-J
P-4
.-JP
--8
,I0
5°F
.F.
p.
> :;; 'tl
t"" I ~ I ..., I:>:> I c.n c.n
12
010
59
03
015
00
80
V ~t•
~\
~~'
.•
~a
w•
~~
'0o
.~
"-
~o
.•
~~
o.
0Jp
..V
~::!
•~
y~
~~
~z
w~
~>
~~
a"
~~
v~
,
~,,;,.
1 a.':E
.
<l2
0
FU
EL
TE
MP
ER
AT
UR
E,
oF.
Fig
ure
9.
Ov
erp
ress
ure
for
Sta
nd
ard
Test
wit
hA
tmo
sph
eric
Init
ial
Ull
age
Pre
ssu
re
AFAPL-TR-72-55
20
160
leo
140
120
•l-I-
~ :::!:..J
..J(f) 100 Z :I:(l. « uw
..J a:w Cl Cla: a: a:::> « «(f) Cl Cl(f) Z ZW
~ ~a: eo(l. (f) (f)a:
~w ~>~ ~0
:.:: (\J (\J
«w(l.
I 60
:;:(l.
<l• -INDICATES EXIT PLATE
RUPTURE
40
o .....- __..-....... ...... .....L ..... ... ...
o 20 40 60 eo 100. 120
FUEL TEMPERATURE 1°F.
Figure 10. Overpressure for Standard Test with JP-4 at 30PSI InitialUllage Pressure
18
AFAPL-TR-72-55
The hazards of initially lean fuel vapor ullages are much more complex and
uncertain. Depending upon the amount and nature of the fuel added, an ullage
can remain nonflammable, become flammable, or be shifted past the rich limit
into a nonflammable condition.
Apparently in the shots using JP-8, 105°F flash point, a small amount of
fuel was added to the ullage which shifted it into a flammable condition. The
overpressures are remarkably similar to overpressures measured during flam
mability tests of the ullages in sloshing fuel tanks previously conducted by
the Air Force Aero Propulsion Laboratory(AFAPL) and reported in technical1report AFAPL-TR-70-65 .
Figure 11 shows the times from projectile impact to peak overpressure for
the standard tests at atmospheric pressure. For the JP-4 data we see that the
times increased rapidly near the rich limit of 51°F to 59°F as previously des
cribed. The times to peak overpressure for the JP-8 show an apparent peak at
a temperature slightly less than the flash point of the fuel, A similar time peak
phenomena was observed in AFAPL-TR-70-65 (See Figure 12). Due to the
limited amount of data available the exact shape of this curve cannot be deter
mined, however, the time peak phenomena was probably due to a transition
from one type of combustion process to another. It should be noted that the
times to the left of the peak were associated with much lower overpressures
than the times to the right of the peak. One might expect the time required to
reach a lower overpressure to be shorter and as the temperature continues to
decrease to the point of no reaction that the time to maximum overpressure
would again increase.
Regression Equations for the Standard Test Results
~ Since the Standard Tests were conducted with several variables including
fuel type, initial temperature, and initial pressure it was desirable to be able
(1) AFAPL-TR-70-65 "Effects of Fuel Slosh and Vibration on theFlammability Hazards of Hydrocarbon Turbine Fuels within Aircraft FuelTanks", E.E. Ott, November 1970
19
> ~ "C t"' I "'3 ~ I .., tv I <:J1
<:J1
•-J
P-4
•-J
P-8
,I0
5°F
.F.
P.
co 0- .. ....=
-(~I 0, 0-, I, ~I
J.~~
I I I , I I I----l
'".::>
u<
tob
U7
59
010
512
0
.10
.40
.30
.50
.20
en 0 z 0 u w en w 0: ::> en en w 0:
0-
0: W > 0 lie <l
tvW
00
- 0 r- w :s i= I ;::!;
':a
.F
UE
LT
EM
PE
RA
TU
RE
,oF
.
Fig
ure
11
.T
imes-
to-P
eak
Ov
erp
ress
ure
for
Sta
nd
ard
Test
wit
hA
tmo
sph
eric
Init
ial
Ull
age
Pre
ssu
re
> I-rj > '"d t'" I ~ I -:)
l\j I Cll
Cll
~
~
~.I: .\.\.
~.
~.
e,6 "-.
~~/'\.
........~
.._~
}.
fJ)
T0
l>-
ST
AT
IC1ARC
IGN
ITIO
NS
OU
RC
Ez 0 u
•-:
SL
OS
HA
T1
7.5
CP
M•
w fJ)
Iw a:
./::> fJ
)3
fJ) w a:
•£l
.
~ cI
•w
/£l
. I2
0 l-
•I
I•
wl\j
~to
-'
/l-
I•
0'
II
II
I,
I,
o2
04
06
08
01
00
120
14
016
0
FU
EL
TE
MP
ER
AT
UR
E(0
F)
Fig
ure
12
.T
imes-
to-P
eak
Rea
ctio
nP
ress
ure
for
JP-8
Fu
elat
One
Atm
osp
her
eIn
itia
lU
llag
eP
ress
ure
(Fro
mA
FA
PL
-TR
-70
-65
)
AFAPL-TR-72-55
to express the test results in an efficient form for later comparison. Appendix II
gives the basis for the development of Figure 13. On this Figure all the Stand
ard Test results are plotted for both fuels. By plotting the overpressure ratio
b. PM versus the fuel/air mass ratio the effect of initial pressure and fuel
PI
type no longer must be considered independently.
A regression equation
6052.6 (F/A)4 - 1104.1 (F/A)2 + 185.8 (F/A) - 1.4
(F/A + 1)2
with a multiple correlation coefficient (R ) of 0.9875 was developed for the data.c
was developed for tests with F /A < 0.105. From the plots of this equation on
Figure 19 it may be observed that for very lean fuel/air mass ratios
(F /A < 0.016) a decrease in RTF results in an increase in the overpressure
ratio. The normal lean flammability limit-is approximately F /A = 0.03,
therefore, any reaction must be as a result of conditions generated by the pro
jectile. Since for F /A < 0.016 6 P M was greater for RT
of 1 inchP F
I
and 4.5 inches compared to RTF of 8 inches it was concluded that more inter
action between the projectile and the liquid fuel occurred at the smaller values
of RTF' It should be noted that the regression equation served only as
33
AFAPL-TR-72-55
~II~~ .
~
~~
0<;>~
~ 0
0
0- a" Hn " JP·4
• -a" HTF , Jp-a0-4.5" HTF,JP-4
• -4:5" HTF,JP'8
6-1"' HT.F,JP4
.-1" HTF,JP-a
7.0
04.0
~
~<l:a::~
ILl~a::
:> ~II)
3.0 ~II)ILl
~a::a. ~a::
~ILl> ~0
~~
2.0 ;i'6-~
EI" ~~a. a.• ILl i<l<l~i:!dQ!
1.0 J:~
~I
~!lI)i
Ii
00 .02 ,04
F FUEL/AIR MASS RATIOA
Figure 19. Overpressure Ratio for Various Fuel Levels
34
"\
AFAPL-TR-72-55
a tool for plotting the three curves of Figure 19 and was not based on a
theoretical insight into the interaction between F /A and HTF •
In the normal flammability region (F /A > 0.03) it may be observed that
~ PM decreased as HTF decreased. The reason for this is not completely
PIknown. However, part of the answer may be that the fuel spray and/or incen-,diary generated vapor together with the initial fuel vapor created a local fuel
rich region which was either slow burning or. nonflammable causing a lower
than normal overpressure. In order to evaluate this Figure 20 was developed
which gives the time to ~ PM as a function of F IA. No clear trend was evi
dent although minimum times occurred near stoichiometric as would be expected.
Another factor to be considered was the release of dissolved oxygen from the
fuel due to agitation caused by the projectile. It is questionable whether this
additional oxygen can be released in sufficient time to affect the reaction. The
foregoing factors could not be completely explained due to the limited amount
of test data.
35
AFAPL-TR-72-55
.60 •
o - a"H TF • JP4
• - a" HTF • JP8
o - 4.5" HTF • JP4
• - 4.5" HTF • JP8
6-I"H TF ,JP4
• - I" HTF ,JP8
.50
••
VI0Z0 .40(J •UJVI
~
rl 0<I 60 .30 • •I- ;:,UJ~ ISIIl- • -II • 0 ~,
I-:::? a:: ,<I .20 ~,
0:EI21J:I
• • 61
• 1-1 0.10 0
VI,
6~ ~• 0
~0
100 .02 .04 .06 .oe .10 .12
~ - FUEL/AIR MASS RATIO
Figure 20. Time to ~PM for Various Fuel Levels (Lean Reactions)
36
AFAPL-TR-72-55
5. Entrance Plate Test (Figure 1a & Table VII)
This test series considered the possibility that various entrance plate factors
might affect the amount of fuel spray produced upon projectile impact. Only tests
where extremely lean initial conditions existed were investigated (F /A :S 0.002)
so that increased reaction overpressure would indicate an increase in fuel spray.
Increasing the diameter of the entrance plate should aJlow more deflection upon
impact and more energy transfer to the liquid for a given fuel level, This as
sumes liquid contact with the entrance plate or DE > 2HTF • Increasing the
thickness of the entrance plate would have. two possible effects. First, more
energy would be absorbed by the plate during penetration of the projectile. Sec
ond, it is a known fact that plate thickness affects incendiary functioning and
therefore the ignition source. From film data of the shots it was seen that the
0,125 inch plate causes the incendiary to burn primarily in the region of the exit
plate. The 0.250 inch plate caused burning near the entrance plate. The 0.060
inch plates failed to ignite the incendiary within the tank. Besides affecting the
region of burning, the entrance plate thickness could possibly govern the amount
of incendiary that is burned within the tank. These effects were considered to
have little effect on reaction overpressures for the 0.125 inch and 0.250 inch
plates used in this series.
The trajectory path to fuel level distance, HTF , was also varied in the test
series. Changes in HTF could have two possible effects. First, the amount of
fuel in contact with the entrance plate would change. Second, the aerodynamics
of the projectile in the ullage may interact with the liqUid/vapor interface pro
ducing more fuel spray as HTF is reduced.
Six shots were conducted during the Entrance Plate Test series. Two shots
(221 and 226) provided no useful information since the entrance plate thickness
(0.060 inch) was insufficient to activate the projectile incendiary, The remaining
tests (222 through 225) and tests 217 through 220 of the Fuel Level test series
are compared on Figure 21, As noted previously only F /A:S 0.002 were con
sidered and the major cause for an increase in reaction overpressure should be
due to an increase in the amount of fuel spray produced by the projectile. It
should be noted that to have any type of reaction with F /A :S 0.002 requires
some fuel spray. Before discussing the test results, it should be realized that
37
AFAPL-TR-72-55
1.8
1,5
o~
'0:: 1.2W0::::Jl/)l/)W0::Q.
5 .9
>oI
~IQ."
.6
.3
o - xe . 125 , HTF' I
e-xE= .125, HTF=4.5
6.-XE=.250,HTF'" I
• - XE= .250. HT~ 4.5
JP-8 WITH F/A ~ .002
i-TEST NO.
0(219)
e(217)e (218)
0(220)
.(224)
6(225)
0(223)
e(222)
oO~------~8~---------~1~9~1/-::4-----
DE- DIAMETER OF STRIKER PLATE IN INCHES
Figure 21. Entrance Plate Test Results
38
AFAPL-TR-72-55
no positive statements are possible considering the limited amount of data avail
able for the several parameters which were investigated. No overwhelming
gross effects were observed, however, the following items should be considered
in the, design of a more detailed experiment.
a. For tests 217 and 218, fuel was not in contact with the entranceplate, yet overpressures were observed. Possible cause being spraygeneration from aerodynamics of projectile or energy transfer fromexit plate to fuel.
b. Upon comparing tests 219 and 220 with 217 and 218 the effectof RTF is unknown.
c. Comparing test 222 with 223 and 224 with 225 the effect of RTFis again questionable.
d. Upon comparing tests 224 and 225 with a 0.250 'inch entranceplate with the remaining tests which utilized a 0.125 inch plate,the former resulted in higher overpressures. Possible cause beingmore fuel spray resulting from the thicker plate.
The major result of this test series was that ullage reactions occurred even
at very low initial fuel/air ratios when subjected to horizontal gunfire.
39
AFAPL-TR-72-55
6. Exit Dry Bay Test (Figure 1b and Table VIII)
Six shots which were entirely exploratory in nature were conducted with a
19 1/4 inches diameter times 4 inches long dry ·bay attached to the exit side of
the standard tank. The results are given on Figure 22. The overpressure
ratios for both the main tank and exit dry bay are shown as a function of fuel/air
mass ratio on this Figure. For comparison shots 207 through 210 of the Fuel
Level Test series with the standard tank configuration are given. All shots were
conducted at comparable initial conditions with the exception of Tests 215 and
216. Test 215 had 4.5 inches of fuel and Test 216 had 8 inches of fuel. Due to
equipment malfunction no dry bay pressures were recorded during these two
tests. All other points had only 1 inch of fuel.
It is obvious from the test results that significant overpressures may be
generated in an exit dry bay with vapor phase projectile hits. Fuel spray is
apparently carried into the dry bay by the wake of the projectile and the ignition
is either by the incendiary of the API projectile or hot gases from the reaction
in the main tank. Upon comparing the main tank overpressures from the
Fuel Level Test series which utilized the standard tank configuration and no
dry bay with the standard tank and dry bay results, a possible trend may be ob
served. The main tank overpressures with an exit dry bay were higher than
without the dry bay. This was particularly true at the lower fuel/air mass
ratios. The reason for this is not known, however, at least part of the reason
may involve the restriction on pressure relief due to the reaction in the dry bay.
7. Combination and Special Test (Table IX)
Table IX gives the results of eight special shots that were conducted in
addition to the six basic test types. The first two tests listed, 101 and 119, are
Standard Tests (Figure 1a) except that the procedure for achieving equilibrium
vapor concentration was not used. This would tend to render the JP-4 Fuel/air
ratio leaner than otherwise expected based on equilibrium conditions. Tests
153 and 154 were also nonequilibrium tests to assess the effect of fuel tank
venting. For these tests the regular procedure for Compartmented Tank Tests
(Figure 1d) was used with the initial ullage pressure at 30 psia. Immediately
before firing (approximately 15 seconds) the ullage was vented to atmosphere
40
AFAPL-TR-72-55
6.0
6R__c -EXIT DRY BAYPI
FUEL LEVEL TEST-HTF = I"(FROM FIG.19)
1.0• -MAIN TANK
0- EXIT DRY BAY
X - FUEL LEVEL TEST
00 .05 .1 .15 .2
F- FUEL/AIR MASS RATIO
A
5.0
4.0
Figure 22 •. Overpressure Ratio for Exit Dry Bay Test with JP-4
41
AFAPL-TR-72-55
so that the pressure at time of impact was atmospheric. It was felt that this
venting procedure would tend to render the JP-4 fuel/air mixture leaner than
that calculated for equilibrium conditions at one atmosphere. Test 230 was
conducted with the 19 1/4 inches dia. X 0.125 inch thick entrance plate and tank
configuration as shown on Figure 1a. The uniqueness of this test with JP-8 was
that the fuel spray system was left running during the shot. The fuel spray
should tend to drive the fuel/air ratio rich.
Comparing the results of the foregoing tests with equilibrium tests the fol
lOWing observations are offered:
a. Test 101 - With a JP-4 fuel temperature of 43°F and equilibrium
conditions an overpressure of 54 PSI would be expected based on the Standard
Test results as shown in Figure 9. An actual overpressure of 84 PSI was re
corded during test 101 which corresponds to a leaner fuel-air ratio or an equi
valent equilibrium fuel temperature of about 28°F. This is a 15°F depression
in temperature (fuel/air mass ratio) due to nonequilibrium conditions.
b. Test 119 - This nonequilibrium test with JP-4 at a fuel temperature
of 85°F resulted in no reaction. Assuming a 15°F temperature depression due
to nonequilibrium gives an apparent fuel temperature of 70°F. Comparing this
temperature with the JP-4 rich limit of about 60°F as given in Figure 9 a reac
tion would not be expected, therefore the results of tests 101 and 119 agree.
c. Tests 153 and 154 - These nonequilibrJium tests with JP-4 were
compared with the equilibrium test results for the compartmented tank as given
in Figure 15. No difference between the two sets of results were observed.
Test 230 - This nonequilibrium test with JP-8 at a fuel temperature of
30°F can not be compared directly to any other equilibrium test. An overall
assessment of the JP-8equilibrium tests indicates an expected overpressure
of less than 20 PSI at 30°F. Due to the fact that the fuel spray system was ac
tive during this test, an overpressure of 33 PSI was recorded.
Tests 227, 228, 229 were a combination of the Entrance Plate Test and
Exit Dry Bay Test with JP-8 fuel at equilibrium. In other words, the configuration
42
AFAPL-TR-72-55
shown on Figure 1b was used with the regular entrance plate (8 inches dia.
X 0.125 inch thick) replaced with a 19 1/4 inches dia. X 0.090 inch thick entrance
plate for test 227 and a 19 1/4 inches dia. X 0.125 inch thick plate for tests
228 and 229. The fuel depth was also varied. These tests were entirely explo
ratory with no unique results observed.
43
AFAPL-TR-72-55
SECTION VI
CONCLUSIONS AND RECOMMENDATIONS
The following conclusions were established from the test program.
1. The standard rich limit was maintained for JP-4 fuel under equilibriumconditions.
2. The standard lean limit was extended for JP-8 fuel and the resultingoverpressure decreased with decreasing temperature.
3. A 1 inch diameter hose, 2 feet long, prevented combustion transfer betweentwo tanks with JP-4 fuel. This hose did not affect the reaction overpressure inthe main tank at 1 ATM initial pressure but did lower the overpressure for the2 ATM initial pressure tests.
4. For compartmented fuel tanks (wall interconnect) combustion is more likelyto be transferred from one compartment to another with fuel vapor lean ullagesthan with rich ullages.
5. A very lean fuel vapor ullage with liquid present does not prevent combustion transfer between compartmented fuel tanks (wall interconnect).
6. Due to unburned gas transfer from the hit compartment to the wall interconnected compartment, a higher than expected overpressure may result ifcombustion transfer occurs. During some tests higher than expected overpressure occurred in both compartments.
7. The distance between the projectile trajectory and liquid-vapor interface(RTF) has an effect on the reaction overpressure. At very low fuel/air ratiosthe overpressure increased as RTF decreased. With F /A > 0.016 the overpressure decreased as RTF decreased.
8. Significant overpressures may be generated in an exit dry bay with a vaporphase projectile hit.
9. Nonequilibrium conditions will alter the expected results based onequilibrium conditions.
When applying the above conclusions to the safety evaluation of JP-4 and
JP-8, one must bear in mind that volatility is the primary difference between
the two fuels. JP-4 has a vapor pressure approximately 50 times larger than
JP-8. This means that under identical conditions a fuel tank containing JP-4
will probably have 30 times as much fuel vapor mass in the ullage as a tank
containing JP-8. In addition, the bulk of the testing was conducted at equilibrium
44
AFAPL-TR-72-55
initial conditions. If equilibrium conditions could be relied upon in an aircraft
fuel tank the comparison of the two fuels is simply a question of knowledge of
fuel tank temperature probability. Since an aircraft fuel tank is in a high
nonequilibrium state, additional assessment is required. Projectile dynamics
and aircraft slosh and vibration tend to make the ullage rich. Venting tends to
render the ullage lean. The combined effect of these opposing factors has never
been investigated in a single test program. It is believed, however, that venting
is dominant. If this is true, JP-8 would be the preferred fuel for the type of
threat investigated in this program. It is therefore recommended that further
investigation be initiated to study these combined effects in detail as well as
those factors which were not completely explainable as discussed in the report.
45
AFAPL-TR-72..,.55
APPENDIX I
TABLES
47
Preceding page blank
.',: ., ., \.'
;';,
I' d Ii'
..,. ex>
TA
BL
EI
ST
AN
DA
RD
TE
ST
TE
ST
:L:U
:wD
E~
DF
HT
FP
IF
/A.6
,PM
.6,T
MR
EM
AR
KS
NR
.F
UE
LF
FF
INC
HIN
CH
INC
HIN
CH
PS
IAP
SI
SE
CO
ND
10
2JP
-451
48
49
80
.12
51
1/2
81
4.3
.16
246
.45
10
3"
6356
56"
""
"1
4.3
.21
81
NA
10
4"
6559
59"
""
"1
4.3
.22
71
NA
105
"59
5555
""
I""
14
.3.1
96
1N
A
10
6"
3632
30"
""
"1
4.3
.10
81
NA
107
"37
3735
""
""
14
.3.1
13
0N
A
108
"37
3535
""
""
14
.3.1
13
56.0
52
109
"4
44
141
""
""
14
.3.1
33
43
.11
7
110
"47
454
4"
""
"1
4.3
.14
74
2.1
75
111
"4
241
42
""
""
14
.3.1
28
57.0
94
11
3"
636
363
""
""
14
.3.2
18
1N
A
120
"25
2222
""
""
14
.4.0
80
85.0
58
12
4"
3433
33"
""
"1
4.5
.10
180
UK
N
11
2"
474
545
""
""
30.0
68
118
.03
0R
UP
TU
RE
DE
XIT
PL
AT
E
114
"63
60
61"
""
"30
.10
017
6.0
77
RU
PT
UR
ED
EX
ITP
LA
TE
,11
5"
777
372
""
""
30.1
39
113
.11
0
116
"89
8790
""
""
30.1
85
103
.37
5
117
"10
51
00
108
""
""
30.2
69
1N
A
11
8"
101
9810
0"
""
"30
.24
41
NA
121
"29
2828
""
""
30.0
42
127
.17
5
> ~ "0 t-< I >-3 ~ I --1
t>:l I C1 <:n
ol'
<0
TA
BL
EI
(CO
NC
LU
DE
D)
TE
ST
FU
EL
TL
TU
TW
DE
XE
DF
HT
FP
IF
/A~PM
6T
MR
EM
AR
KS
NR
.0
0
Fo
fF
INC
HIN
CH
INC
HIN
CH
PS
IAP
SI
SE
CO
ND
122
JP-4
3231
318
0.1
25
11
/28
20.0
68
117
.08
1
32"
""
I
"25
..0
58
123
"34
3214
4.1
03
125
JP-8
11
211
211
2"
""
"1
4.5
.04
458
.12
510
50F
.P
.
127
"10
611
211
2"
""
"1
4.4
.03
855
.11
4
128
"98
9910
0"
""
""
.02
94
0.3
75
129
"97
9596
""
""
".0
28
42.3
00
130
"10
697
100
""
""
".0
38
56.1
33
131
"96
9010
0"
""
""
.02
831
.45
4
132
"88
8485
""
""
".0
22
28.2
33
133
"80
7777
""
""
".0
17
16.2
42
134
"74
7271
""
""
".0
14
19.2
93
126
"11
11
14
114
""
""
10.0
62
15.0
66
> :;; 'tl t"' I >-,l :lJ I --1 .., I c.n c.n
CJ> o
TA
BL
EII
EX
TE
RN
AL
LY
CO
NN
EC
TE
DT
AN
KT
ES
T
TE
ST
FU
EL
TL
TU
'!WD
EX
ED
FH
tFP
IF
IAP
MT
M6
PC
6T
C8
PC
RE
MA
RK
SN
R.
of
of
FIN
CH
INC
HIN
CH
INC
HP
SIA
PS
IS
EC
ON
DP
SI
SE
CO
ND
PS
I
13
5JP
-424
24
248
0.1
25
11
/28
14
.5.0
76
81.0
62
5.6
00
5
13
6"
282
828
""
""
14
.5.0
85
78.0
44
8.7
80
8
13
7"
30
30
30
""
""
30
.04
39
6.2
73
15
.93
21
5
13
8"
353
53
5"
""
"3
0.0
49
96
.11
83
.14
03
RU
PT
UR
ED
EX
ITP
LA
TE
13
9"
3736
34
""
""
30
.05
2HO
.68
21
91
.57
19
14
0"
3939
318
.12
5"
"3
0.0
45
10
4.1
44
.17
44
RU
PT
UR
ED
EX
ITP
LA
TE
)
'Tj
) 'd t" ~ I --l ""I '" '"
'" ...
TA
BL
EII
I
CO
MP
AR
TM
EN
TE
DT
AN
KT
ES
TU
SIN
GJP
-4
TE
ST
FU
EL
TL
TU
TW
DF
HT
FP
IF
/All
.PM
ll.T
Mll
.PC
ll.T
Cll
Pe
RE
MA
RK
SN
R.
of
of
OF
INC
HIN
CH
PS
IAP
SI
SE
CO
ND
PS
IS
EC
ON
DP
SI
14
1JP
-428
2624
1.5
81
4.4
.08
668
.05
01
4.1
20
14
14
2"
30
292
91
.58
14
.4.0
92
62
.04
01
3.1
16
13
14
5"
49
474
71
.58
14
.2.1
55
53
.06
51
2.3
20
12
19
4"
343
23
21
.58
14
.4.1
02
66
.06
155
.07
45
CO
MB
US
TIO
NT
RA
NS
FE
R
19
5"
36
35
35
1.5
81
4.4
.10
?1
81
.32
10
.53
61
0
19
9"
444
44
31
.58
14
.4.1
32
36.3
62
13
1.2
91
3
20
0"
43
43
42
1.5
81
4.4
.12
8.
47.0
67
10
.87
61
0
14
3"
32
293
01
.58
27.0
50
11
2.1
79
98
+*
.17
21
2*
RE
AD
OU
TO
FF
SC
AL
EC
OM
B.
TR
AN
S.
14
4"
353
23
21
.58
29..
05
01
26
.08
61
45
.10
65
CO
MB
.T
RA
NS
•
14
6"
515
05
01
.58
30.0
75
14
2.0
71
16
0.0
96
7
14
7"
55
54
53
1.5
82
3.5
.10
68
2.0
35
20.3
66
20
14
8"
56
54
54
1.5
820
.12
97
0.0
41
17
.31
61
7
14
9"
56
54
54
1.5
826
.09
81
24
.09
910
5.1
61
10
CO
MB
.T
RA
NS
.
15
0"
56
53
54
1.5
826
.09
81
40
.05
625
.28
025
15
1"
57
56
56
1.5
82
7.5
.09
41
22
.0('
926
.36
02
6
15
2"
56
56
56
1.5
830
.08
413
6.0
50
115
.05
51
0C
OM
B.
TR
AN
S.
19
6"
363
43
51
.58
30
.05
11
34
.22
019
5.2
28
14
CO
MB
.T
RA
NS
.
19
7"
43
41
41
1.5
825
.07
21
08
.04
420
.16
020
19
8"
3741
41
1..5
81
6.1
00
84
.05
115
.09
21
5
20
1"
43
43
43
1.5
83
0.0
60
64
.11
01
70
•08
25
CO
MB
.T
RA
NS
.
20
2"
47
474
71
.58
30
.06
81
40
.05
625
.28
025
;.. :;; 'tJ t-< ~ I ..., '"I '" '"
'" '"
TA
BL
EIV
CO
MP
AR
TM
EN
TE
DT
AN
KT
ES
TU
SIN
GJP
-8,
11
8°F
FL
AS
HP
OIN
T
TE
ST
TL
TU
TW
DF
HT
FP
IF
/Ab.
PM
b.™b.
PC
b.T
C8
Pc
RE
MA
RK
SF
UE
LN
R.
of
of
OF
INC
HIN
CH
PS
IAP
SI
SE
CO
ND
PS
IS
EC
ON
DP
SI
15
5JP
-81
24
12
41
24
1.5
81
4.5
".0
36
32
.26
31
4.4
48
14
15
6"
10
41
04
10
4"
"1
4.5
.02
017
.19
013
.44
01
3
15
7"
989
494
""
14
.5.0
17
39.2
59
63
.20
41
2C
OM
BU
ST
ION
TR
AN
SF
ER
15
9"
8884
84"
"1
4.5
.01
218
1.0
70
18
1.1
60
18
16
1"
8080
79~,
"1
4.5
.00
91
4.8
60
I1
4.9
46
14
16
3"
11
91
16
11
4"
"1
4.5
.03
1I
28.0
5[)
11
.30
011
18
4"
566
365
""
14
.6.0
04
55.3
57
81.4
40
6C
OM
B.
TR
AN
S.
18
5"
7480
80"
"1
4.6
.00
73
2.4
37
75
51
41
0C
OM
B.
TR
AN
S.
18
6"
808
786
""
i4.6
.00
918
.26
51
31
.17
01
3
18
8"
60
63
62
""
14
.5.0
05
2-
2-
2
18
9"
5555
54"
"1
4.5
.00
41
0.4
80
9.4
40
9
19
0"
33
30
30
""
14
.4.0
02
6.4
44
5.H
45
19
3"
323
030
""
14
.4.0
02
2.5
.27
40
00
15
8"
959
29
4"
"3
0.0
07
8.3
40
8.4
56
8
16
0"
948
888
""
10.0
22
18.1
54
9.3
80
9
16
2"
14
31
42
14
1"
"30
.02
91
04
•40
42
04
.42
21
2C
OM
B.
TR
AN
S•
16
4"
10
61
03
10
3"
"1
0.0
31
27.0
64
8.1
24
8
16
5"
10
496
96
""
20.0
14
64.4
20
106+~
.36
41
2*
RE
AD
ING
OF
FS
CA
LE
CO
MB
.T
RA
NS•.
18
7"
717
47
2"
"20
.00
50
00
0-
19
1"
33
303
0"
"1
2.0
02
00
00
0
19
2"
333
03
01
.5"
18
.5.0
01
00
00
0
;J> ;! 'd t-< I >-l~ I """ '" I '" '"
Cl1 c..:>
TA
BL
EV
CO
MP
AR
TM
EN
TE
DT
AN
KT
ES
TU
SIN
GP
RO
PA
NE
TE
ST
VO
L.
TU
PI
F/A
t::.
.PM
t::..
TM
t::..P
Ct:
:..T
C8
PC
RE
MA
RK
SF
UE
L%
NR
.o
fP
SIA
PS
IS
EC
ON
DP
SI
SE
CO
ND
PS
I
16
6C
3H8
2.2
38
14
.6.0
35
81.0
45
23.1
88
23
CO
MB
.T
RA
NS
.1
67
"1
.83
*8
14
.6.0
28
67.7
79
13
1.8
26
10
*L
IQU
IDC
3H
8M
AY
HA
VE
LE
AK
ED
INT
OT
AN
K
16
8"
1.0
01
31
4.6
.01
50
00
00
16
9"
1.9
31
01
4.6
.03
02
-0
00
17
0"
2.3
81
11
4.6
.03
736
.08
527
.24
027
171
"<
'3.8
01
21
4.6
<.0
60
64.0
55
32
.22
032
,
17
2"
3.8
01
41
4.6
.06
09
6.0
36
32.1
96
32
17
3"
8.1
522
14
.6.1
35
78.0
63
32
.20
83
2
17
8"
8.8
10
14
.6.1
47
00
00
0
17
9"
8.0
10
14
.6.1
32
16.4
30
15.5
12
15
17
4"
1.8
223
30.0
28
00
00
0
CO
MB
.T
RA
NS
.-
--1
75
"2
.41
202
4.5
.03
8>
2>
.50
01
88
_.6
40
3R
UP
TU
RE
DE
XIT
-1
76
"2
.41
2225
.03
81
-0
00
177
"I
8.8
202
2.5
.14
7j
15
6.0
29
7.5
.05
07
.5R
UP
TU
RE
DE
XIT
,I
18
0"
8.0
13
20.1
32
13
4.0
39
45-
.21
24
5
18
1"
2.5
211
8.0
39
16
.57
015
.58
41
5
18
2"
2.6
721
25.0
42
13
2.1
40
18
5.4
78
5C
OM
B.
TR
AN
S.
18
3"
3.0
028
25.0
47
00
00
0
> >rj > "d t"' I ~ I -'J '"I Cl1
Cl1
en oj:>.
TA
BL
EV
I
FU
EL
LE
VE
LT
ES
T
TE
ST
FU
EL
TL
TU
TW
DE
XE
DF
HT
FP
IF
/AL
lPM
.6.™
RE
MA
RK
SN
R.
of
of
of
INC
HIN
CH
INC
HIN
CH
.P
SIA
PS
IS
EC
ON
D
203
JP-4
3028
288
0.1
25
54
.51
4.5
.09
172
.06
1
204
"33
2828
""
54
.527
.05
294
.23
5
205
"35
34
34
""
54
.530
.04
910
8.3
17
206
"35
3636
"II·
54
.51
4.5
.10
387
.12
0
207
"3
33
232
""
8.5
11
4.5
.09
968
.20
8
208
"34
3232
""
8.5
130
.04
883
.31
3
209
"36
3636
""
8.5
130
.05
110
5.0
88
210
"34
3636
""
8.5
11
4.5
.10
166
.07
3
217
JP-8
4141
41"
"5
4.5
14
.4.0
02
12
.48
3(H
8°F
.P.)
218
"4
64
44
4"
"5
4.5
30.0
01
24.2
98
219
"4
24
24
2"
"8
.51
14
.4.0
02
18.5
86
220
"4
04
04
0"
"8
.51
30.0
01
9.1
76
> ~ "tI t"" I ~ I -.1
t>:l I en en
CJ1
CJ1
TA
BL
EV
II
EN
TR
AN
CE
PIA
TE
TE
ST
TE
ST
FU
EL
TL
TU
TW
DE
XE
DF
HT
FP
IF
/A.6
.PM
.6.T
MR
EM
AR
KS
NR
.o
fo
fo
fIN
CH
INC
HIN
CH
INC
HP
SIA
PS
IS
EC
ON
D
221
JP-8
40
40
40
19
1/4
0.0
60
54
.51
4.4
.00
20
0N
OIN
CE
ND
IAR
Y(1
180
F.
P.)
FU
NC
TIO
N
222
"38
383
81
91
/40
.12
55
4.5
".0
02
2-
223
"4
04
039
19
1/4
0.1
25
8.5
1"
.00
218
.23
5
224
"4
04
04
01
91
/40
.25
05
4.5
".0
02
24.2
44
225
"28
2828
19
1/4
0.2
50
8.5
1"
.00
120
.25
6
226
"28
2828
19
1/4
0.0
60
8.5
11
4.5
.00
10
0N
OIN
CE
ND
IAR
Y
'iF
UN
CT
ION
> :; 't!,
t"' I ~ I --1~ I CJ
1CJ
1
en <0>
TA
BL
EV
III
EX
ITD
RY
llA
.YT
ES
T
TE
ST
FU
EL
TL
TU
TW
DE
XE
DF
IIT
FP
IF
/AI:
;P
MI:
;TM
I:;
Pc
I:;T
C;:;
Pc
RE
MA
RK
SN
R.
of
OFo
fIN
CH
INC
HIN
CH
INC
HP
SIA
PS
IS
EC
ON
DP
SI
SE
CO
ND
PS
I
21
1JP
-43
33
33
48
0.1
25
8.5
11
4.5
.09
9G
8.O
G[i
50
oO.
5G8
21
2"
30
30
30
""
8.5
12
0.O
GG
82
.07
832
.18
80
21
3"
313
0:)0
""
8.5
1:1
0.0
·1'1
10'1
.22
831
.42
81
0
21
4"
3Z3
23
2"
"80
:)1
22
.OG
2G
3.
14fi
40
•~G;)
4
215
"4
04
04
0"
"5
4~;)
Jol.
4.1
20
-ID.H
ZU
NK
UN
KU
NK
{E
QU
IPM
EN
TM
AL
FU
NC
TIO
N}
21
6"
44
414
1"
"1
.58
14
.'1
•J:
\Z5
2.1
23
UN
KU
NK
UN
KD
RY
RA
Y,
NO
i\JEA~unF:MENTS
;t> "'1 :» "d r , >-i
:;;:J , -, '", ;;;1
~,
'".."
TA
BL
EIX
CO
MB
INA
TIO
NA
ND
SP
EC
IAL
TE
ST
S
TE
ST
FU
EL
TL
TU
TW
DE
XE
DF
HT
FP
IF
/Al:
,PM
l:,T
Ml:
,PC
l:,T
C8
PC
RE
MA
RK
SN
R.
"F"F
"FIN
CH
INC
HIN
CH
INC
HP
SIA
PS
IS
EC
ON
DP
SI
SE
CO
ND
PS
I
101
JP-4
43
41
42
80
.12
51
.58
14
.3.5.
.13
184
.04
0N
AN
AN
AN
ON
EQ
UI-
LIB
RIU
MV
AP
OR
119
"8
58
38
3"
""
"1
4.2
5..3
86
00
NA
NA
NA
"1
53
"5
65
555
""
""
14
.2*
(1)
54
.0"1
71
1.2
80
11
*R
ED
UC
ED
FR
OM
30JU
ST
BE
FO
RE
Fil
lIN
G
15
4"
54
52
52
""
""
14
.2*
'(2
)65
.03
8·.
11
.38
21
1"
.'22
7JP
-828
2828
19
1/4
0.0
90
8.5
11
4.5
.00
10
00
00
EN
TR
AN
CE
PL
AT
El1
S"F
.P.
AN
DD
RY
BA
Y
228
"28
2828
"0
.12
55
4.5
14
.5.0
01
19
.34
49
.13
29
"
229
"30
30
30
""
1.5
81
4.5
.00
111
.43
S2
.25
22
"23
0JP
-8U
S"F
.P.
303
03
01
91
/40
.12
51
.58
14
.5~.001
33U
NK
NA
NA
NA
EN
TR
AN
CE
PL
AT
EW
ITH
FU
EL
SP
RA
'"
;.- :;; "0 t'" I ~ I .." '"I '" '"
(1)
'F/A
(2)
F/A
.08
5A
T30
PS
IA&
.18
5A
T1
4.2
PS
IA
.08
2A
T30
PS
IA&
.'17
6A
T1
4.2
PS
IA
AFAPL-TR-72-55
APPENDIX II
DETERMINATION OF INFLUENCE OF INITIAL ULLAGECONDITIONS UPON PEAK REACTION PRESSURE
System: Gases in the ullage of a rigid fuel tank.
Assumptions:
1. Gases obey perfect gas law, PV = nRT
2. Heat of reaction added to gases, no heat los s to tank
3. Specific heats of reactants and. products are constantand equal .
4. System is homogeneous and at equilibrium
5. Increase in gas moles after combustion can be ignored
Using the perfect gas law as applied to a constant volume process we have:
pY; PF~ ,(PI + 6. P) / (TI + 6.T) ( 1 )T
IT
F
Where:
PI initial system pressure
T1
= initial system temperature'
P F= final system pressure
TF final system temperature
6.P reaction pressure rise (PF - PI)
6.T reaction temperature riSe'7(TF - T1)
58
AFAPL-TR-72-55
Solving Equation 1 for ~ T yields
~T (2)
With the equation
Q = MC~T
Where:
Q = heat releasedM = system massC = system specific heat
(31
For fuel lean reaction (4) < 1) it may be stated th~t the heat released (Q)
will be proportional to the amount of fuel in the ullage. Since the amount of fuel
is proportional to the fuel vapor density, we have Q a Pv ITI" With the sys
mass (M) proportional to PI/T
and the system specific heat constant,, I
Equation (3) becomes:
~T or (4)
Substituting Equation (4) into Equation (2) yields
PvPITI
Since the fuel/air mass ratio (F IA) is, P
F IA :::::: PV for PV << PII
and assuming equal molecular weight for both the fuel and air
We find that
~ P a ~ (r) for 4>< 1PI I
For fuel rich reaction (4) > I), the heat released (Q) will be proportional
to the oxygen available and since the oxygen available is proportional to
to we see that
59
.AFAPL-TR-72-55
The system mass (M) will be proportional to(Pr)and with the system specific
heat constant, Equation (3) becomes: T. r
(5l
or ~T a
Substituting Equation (5) into Equation (2) yields
(6)
PISince -=P~r---=--:=P=-v- F + A
AF + 1 assuming equal molecular weightA
for both the fuel and air we obtain1
T X (r + 1 )
In summary, for the hydrocarbons of interest, we would expect correlation
of the various parameters as shown below:
Ttjil>P= e..2
I 1-( F + I)- _: PI rJr
E ._' Ii,6P . e i._1-- ..J
'\ ..J'PI 0
TIc0,Ic II
.c l0 Il! (F/A) -a..~ (,J!._0..J T1 0::: 1
(,J
TI,< T120.- 8...- 0
I W 0I E 0G ° Ia -I-, .c0,
l.l °0Ei ~I"'. °0 0'°0 U;g zo;Za I ,I g II ,
n9
.03 .0167 .28F/A
60
AFAPL-TR-72-55
APPENDIX ill
REGRESSION ANALYSIS
A stepwise multiple regression analysis program was used to determine
prediction equations and these equations have been noted in the report. These
equations were developed for the data based on the approach of least squares.
Certain basic assumptions were required before the .program could be used.
It must be assumed that the model can be properly expressed by using linear
coefficients in the regression equations. All variables must also be assumed
to be multivariate normally distributed.
Several models were used in the. regression analysis and were based on the
parameters developed in Appendix II which were;
,1.. ,T F/A and 1
F/A+l
6PMThe first model was developed to predict the overpressure ratio --="';;:;'PI
for the standard test results as given on Figure 13. The data points included
all the points for both JP-4 and JP-8 except as noted on Figure 13. The fol
lowing equations were the best generated for this data set.
The multiple correlation coefficient (R ) is a measure of the significance or thecworth of the equation for prediction, As may be seen there was little difference
between the two equations, This was expected since the range of temperatures
used in the test program was smalL Equation (2) was selected as superior
based on the results of Appendix II, This was an item which should be verified
by additional testing over a wide temperature range.
The next model developed was for the data points given on Figure 19. The
![AFATL-TR-72-401__Developement of 20MM and 30MM Plastic-Aluminium Cartridge Cases [1972]](https://static.documents.pub/doc/80x56/577cdb301a28ab9e78a78ed1/afatl-tr-72-401developement-of-20mm-and-30mm-plastic-aluminium-cartridge.jpg)
