00 memorandum report no. 2775 t burning rates of … · 00 memorandum report no. 2775 t"...
TRANSCRIPT
*1z
00 MEMORANDUM REPORT NO. 2775
t" BURNING RATES OF STANDARD ARMY PROPELLANTS
IN STRAND BURNER AND CLOSED CHAMBER TESTS
• Bertram B. GrollmanCarl W. Nelson
A ugust 1977 . " _
Approived for public release; distribution unlimited.
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€ .USA ARMAMENT RESEARCH AND DEVELOPMENT COMMAND' USA BALLISTIC RESEARCH LABORATORY
ABERDEEN PROVING GROUND, MARYLAND
4
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Do not return it to the originator.
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Additional copies of this report may be obtained Ifrom the National Technical Information Service,
U.S. Department of Commerce, Springfield, Virginia
22151.
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ea
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I
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II
The findings in this report are not to be construed as Iian official Department of the Army position, unlessso designated by other authorized documents.
Thý uo of trade namea or mm~u~facturers, n'amea in thLii reportkwos -L't onntitut i~ndoreement of cmy -omUwfrcjaj 1,tr'odi4 t.j
SECURNITY CLASSIFICATION OF THIS PAGE Mon. Data N-moO ________________
REPORT DOCUMENTATION PAGE KZAOR COVPLICTIRFORM
14. REORIT ORIbaAENC AA.&fOE5IfdIw. GOV ACRn~Uh OIlS..) IL SECUIPCTY CATLASS (.1(UI t9we
14. Tu~ITE(adlo""* STATMEN OF1 REPOR A PRID OVRE
Car W SU PL M NTARY AN D RESO. R G A E E ETESO EC .T S
IS. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ AE &E WOROS UNITn.. NUMBERSIn~.w dIwtiyb btke,,
BUrnn SArmBatlsieesacabrtrAbrenPropellaun-nt~an I6 I&AUZ
Clo EsednhaoberAvneNS%;WStrxandra Burner 3 A
Burning rate RES(I data"O detrmne ovetrteffn OtyyarsaoatteBalsi
referene for.uuj curentineast;igatrions.It colmparesdtadbrerad.o
chmeP ae frtesm ropellant. -
Clo(continuedr
Strand Burner . PI O 65GOLT
ý A1&r R C~ r = 2tw ot m r ro ob ffECURITYr CLAd VICATION 67 WTNISbw GEjm k
SIFIED89CUVAY PICATION Of THIS PAQ@Eh~i~ 000 Mkfmis
" Standard army gun propellants (M1, M2, MS, M6, M8, M10, and M17) werere-extruded into 3mm (1/8 in.) and 6mm (1/4 in.) strands for strand burnertests at pressures of 3.4 to 310 KPa (S 0 to 45,000 psi) and in closedchamber tests at densities of loading 6, of 0.089, 0.174, and 0.258 g/cc.Fifteen additional lots of standard prop Ilants were tested in the closedchamber at densities of loading of 0.084 and 0.140 g/cc.
The report presents the raw data, mqthod of calculation for burningrate, and coefficients for various burning rate equations. The report alsoproposes an empirical relationship between the propLellant flame temperatureand the burning rate parameters.
2. UNCLASSIFIEDSECURITY CLASSIt'ICATION OF TMI3S PAaGEW"?" . Does 9 r,* d)
- -~-----.- - - ------------ - ~ -
TABLE OF CONTENTS
Page
LIST OF ILLUSTRATIONS ................... 5
LIST OF TABLES. .......... ..... ...................... 7
I. INTRODUCTION .............. ......................... 9
II. DESCRIPTION OF EQUIPMENT ............ ................. 9
III. EXPERIMENT MAIN TEST .......... ................... ... 11
IV. RELATIONSHIPS OF THE COMBINED RESULTS ............... ... 11
V. PREVIOUS TEST IN CLOSED CHAMBER AT BRL ...... .......... 16
VI. BURNING RATE DATA FROM OTHER AGENCIES ............... ... 16
VII. CONCLUSIONS .............. ....................... ... 31
REFERENCES ........... ....... ....................... 33
DISTRIBUTION LIST ............ .................... 35
Si
J 3
LIST OF ILLUSTRATIONS
Figure Page
1A Correlation of Burning Rate Coefficientwith Flame Temperature (English Units) .... ........... 19
1B Correlation of Burning Rate Coefficientwith Flame Temperature (Metric Units) .... ........... ... 20
2. Burning Rate Comparison for M1 ..... ............... .. 22
3. Burning Rate Comparison for M2 ....... ............... 23
4. Burning Rate Comparison for MS ..... ............... .. 24
S. Burning Rate Comparison for M6 ....... ............... 25
6. Burning Rate Comparison for M8 ....... ............... 26
7. Burning Rate Comparison for 1l0 ...... .............. .. 27
8. Burning Rate Comparison for M17 ...... .............. .. 28
?,0 VO 2rA
I "*
] LIST OF TABLES
Page
I. Description of Standard Lots ..... .............. ... 12
II. Burning Rate Results for BRLExtruded Propellants ....... .................. ... 13
IIA. Propellant Burning Rate ...... ..... ................ 14
III. High Pressure Strand Burner Data .... .............. 1S
IV. Least Square Parameters for Various Burning RateEquations Using Combined Strand Burner and ClosedChamber ResultsA English Units ..... ................... 17B Metric Units .... ................... 18
V. Description of Additional Closed Chamber Lots ... ..... 21
7
I. INTRODUCTION
"The chemical system of powder and gas presents a complex in whichchemical reactions occur at high speed with remarkable precision. Thefree energy of powder gas is much less than that of powder, and thereaction between them, when once initiated, goes forward rapidly--incommon parlance, the powder burns."
The National Defense Research Committee published in 1946 asummary of their investigation in intTrior ballistics in "HypervelocityGuns and the Control of Gun Erosion." The burning rate data forseveral propellants determined in closed chambers disagreed with testgun results. This was attributed to ignition problems and no~ewhatdifferent formulations in the test propellants. R. H. Kent ' atAberdeen proving Ground and BRL had studied the closed chamber data from1925 on, and when a high pressure strand burner was acquired in 1950,suggested that the same propellants be used in both devices. Theseexperiments were conducted and the results published in the monthly BRLProgress Reports (1953-1956) which had limited distribution. Standardarmy gun propellants (Ml, M2, MS, M6, M8, M10, and M17) were re-extruded
* into 3mm (1/8 in.) and 6mm (1/4 in.) strands for strand burner tests atpressures of 3.4 to 310 MPa (500 to 45,000 psi) and in a closed chamberat densities of loading (A) of 0.089, 0.174, and 0.258 g/cc. Fifteenadditional lots of standard propellants were tested in the closedchamber at densities of loading of 0.084 and 0.140 g/cc. Propellantdescription sheets are available for all the propellants.
This paper describes the experiments, the test data, and thederived burning rates. The results of tests at several other agenciesare compared to those of the BRL standard tests.
II. DESCRIPTION OF EQUIPMENT
A. STRAND BURNER
The strand burner, used for the experimental firings, was manufact-ured by Autoclave Engineers aad is capable of firing propellant samplesat pressures up to 345 MPa (50,000 psi). The reaction chamber is 5.08cm (2 in.) in internal diameter and 25.4 cm (10 in.) long. Theauxill ary surge 3 tank associated with the system has a capacity of0.014m (0.5 ft. ).
1F. C. Kracek, "Hypervelocity Guns and the Control of Gun Erosion,"
Parr II BalZistics, Chapter 2, NDRC, Washington, D. C., 1946, pp. 21-53.2R. H. Kent, "Report on Determination of Interior Ballistic Data by
Closed Char'ber Experiments in Connection with Project RB158,"1 BRLR 32,Jan 1936.
3R. H. Kent, J. P. Vinti, "Cooling Corrections for Closed Chamber Firings,"BRLR 281, Sep 1942. (AD #491852)
9
--- J
The propellant samples fired varied in diameter from 0.25 cm(0.10 in.) to 0.64 cm (0.25 in.) and were about 15 cm (6 in.) long. Theywere inhibited by dipping in a vinyl resin solution. Each grain had fourholes laterally drilled through it with a number 75 drill. In the firsthole, a nichrome wire was inserted to ignite the grain. The other holeshad 0.5 ohm fuse wire inserted through them to activate time intervalrecorders. The holes were drilled with the aid of a jig and, thus, thedistances between holes were quite accurate. For fast burning propellants,1.6 megacycle Potter counters were used; for slow burning propellants,Standard Electric 0.01 second clocks were used to measure the timeintervals.
The nominal distance between two adjacent fuse wires was 5.08 cm(2 in.). Two time intervals were measured per round fired. The firsttime interval recorded was for the first 5.08 cm (2 in.) of burning andthe second time interval was either for the second 5.08 cm (2 in.) orthe whole 10.16 cm (4 in.) of burning.
The pressures were read from Bourdon gages. The scale divisionsare 20 psi for the low range (0 to 3,000 psi), 500 psi for the middlerange (0 to 15,000 psi) and 1,000 psi for the high range (0 to 50,000psi). Because the system had slow leaks, it was over-pressurized andfired when it reached the desired pressure. While the grain was burning,the pressure increased slightly and was.bled off into the surge tank.This surge was noticeable on the Bourdon gage only for very low initialpressures. The overall accuracy is estimated to be within 2%.
B. CLOSED CHAMBER
The closed chamber was manufactured by DuPont. It is capable offiring propellant samples up to pressures of 310 MPa (45,000 psi). Thereaction chamber is 3.2 cm (1.25 in.) in diameter and about 6.6 cm(2.6 in.) long with a volume of 59 cc (3.6 in. ).
The propellant samples were fired as received, neither selectedfor uniformity nor inhibited. A gage plug containing a double piezo-electric gage and a gas release valve was screwed into one end of thechamber. An igniter plug with insulated leads was screwed into the otherend. The leads were joined with 0.013 cm (0.005 in.) diameter tungstenwire, and the wire was wrapped with 0.25 g of thread propellant. Thepropellant charge was wrapped in a silk bag surrounding the igniter.Firing was initiated by applying 24 volts across the external igniterplug leads. Records were taken of the output of the double piezo-electric gage. One set of output leads was attached to a drum cameraand a dual beam cathode ray oscilloscope to record pressure and rate ofchange of pressure versus time. The other set of output leads wasattached to a Dumont No. 235 CRO to record pressure versus rate of changeof pressure. The rates of change of pressure were obtained by electricallydifferentiating the pressure gage output.
SO
III. EXPERIMENT MAIN TEST
The re-extruded standard propellants are described in Table I,including basic propellant lot and hexane densities.
For the strand burner test, both size cords were cut into 15 cm(6 in.) lengths and inhibited by dipping in a vinyl resin solutionthree times. The strands were burned at nine different pressures. Theresults are shown in Table II. For the smaller diameter grains, boththe burning rates determined for the initial segment and the finalsegment of the seven sample propellants agreed within 2%, except for theM8 propellant at 207 MPa (30,000 psi) and 241 MPa (35,000 psi). Therates determined for the larger grains were somewhat slower than therates determined for the corresponding smaller propellant grains. Thiswas attributed to an increase in retained volatiles. Also, there wereseveral failures due either to poor retention of coating or physicalbreakup during pressurization or burning. This series was fired during1953-1954.
Several years after these tests, the Harwood High Pressure StrandBurner was transferred from the Bureau of Mines to BRL. During theproofing of the apparatus, the few remaining strands from the previousexperiment were tested and the limited results are shown in Table III.
For the closed chamber test, the smaller size grains were cut intoS cm (2 in.) lengths. Five, ten and fifteen gram charges were fired induplicate for each propellant. The igniter was an 0.25 g thread propellant,having a diameter of 0.013 cm (0.005 in.). For the Ml, M6, M1O and M17samples, the ignitor was re-extruded from an M1 composition; for theM2 and MS samples, the ignitor was re-extruded from an M2 composition;and for the M8 sample, the ignitor was re-extruded from an M8 composition.The pressure was measured with a stacked quartz piezo-electric gagemounted on a piston. This series of propellant samples was fired July1954. The burning rates w re calculated using the method reported inBRL Report 546, J. Wiegand and are tabulated in Table II. Table IIAcontains the combined data and can be used for reference in English orMetric Units.
IV. RELATIONSHIPS OF THE COMBINED RESULTS
The burning rates determined in the strand burner and closed chamberwere combined as shown in Table II and were used to fit the followingexpressions:
4.'4 . H. Wiegand, "A Method for the CaZlcuation of the Burning Rate ofPowders from dp/dt Records for Close? Chanbers," BRLR 546, May 1945.
11
oem to No of1NN *! . .S 44 %a Io.4 r
*I WWI .A N0ý
IL- a -v A v'
0i LON r * f 10 too 000
4-14
NN. N-W*
Ct NN 0! I ON - :.
On cc 4.4
0.1 00Nh 00
NOn A 0 t4 o
0N0 f N 0 C
-14.
PNNN 00 .0 P
C4
r4 LA 0 a arq a- -T N0 m m
C; 0'
10 61aCN N O N0 V~~NO4~~O4 N0 N 9O N Oo NJI ~~~~0
N . O 0 0 NO- * 4
NO o
~a ao -nSIs
C)~ N) :3 o 'o~N 4; u4
- as
Ncc...00
0. CA WN w N. CLgoa
N12N.
Table II. Burning Rate Results for BRL Extruded Standard Propellants(Rates in./s)
Prope I lant TestRun 5001 10,000 15.00 20,000 25,000 30,000 35,000 0,,000 45,000 9si
T465 MI So 1.13 1.74 2.21 3.30167 M2 58 1.65 3.14 4.48 5.48 6.67 7.96"169 M5 SB 1.71 2.76 4.00 4.99 6.30 7.55 8.44 8.99 10.21471 M6 SB .65 1.28 1.85 2.47 3.04 3.64 4.03 4.73 5.13473 M8 SB 2.10 3.75 5.57 6.76 7.56 9.30 10.52 11.28475 IO So .90 1.61 2.33 3.27 4.00 q.50 5.20 5.82 6.57477 M17 So 3.20* 7.00* 16.00* 20.00*
T466 MI So .59 1.17 1.68 2.26 2.89 3.36 4.10 4.59 5.12cc-I .65 1.19cc-2 .65 1.19 1.82cc-3 .69 1.19 1.72 2.29 2.89Se-cc .65 1.18 1.74 2.27 2.89 3.36 4.09 4.59 5.12
T468 M2 So 1.53 2.94 4.12 5.47 6.63 7.77 9.46 10.37 11.91cc-I 1.34cc-2 1.53 2.74 4.12 5.62cc-3 1.72 2.82 4.12 5.33 6.51 7.73SB-cc 1.53 2.83 4.12 5.48 6.54 7.75 9.46 10.37 11.91
T470 M5 So 1.41 2.78 3.99 5.47 6.67 7.92 8.43 9.95 11.86cc-I 1.30cc-2 1.46 2.55 3.73cc-3 1.57 2.60 3.71 4.72 5.74 6.70SB-cc 1.43 2.64 3.85 5.08 6.36 7.54 8.43 9.95 11.86
T472 146 SB .68 1.31 1.91 2.53 3.13 3.97 4.50 5.05 5.51cc-I .72cc-2 .66 1.24 1.97cc-3 .85 1.54 2.13 2.81 3.52SB-cc .72 1.36 1.98 2.62 3.26 3.97 4.50 5.05 5.61
T474 M8 So 2.00 3.75 5.50 6.78 8.25 12.44 14.12cc-I 1.86cc-2 2.20 3.83 5.60cc-3 2.15 3.59 5.31 6.84 8.39 9.90SB-cc 2.04 3.73 5.47 6.80 8.31 9.90 11.30 12.44 14.12
T476 1410 SB .91 1.68 2.50 3.29 3.90 4.80 5.28 6.03 6.63cc-I .89cc-2 .89 1.47 2.11cc-3 1.02 ".59 2.19 2.87 3.54SB-cc .92 1.60 2.33 3.15 3.78 4.80 5.28 6.03 6.63
T478 1417 SB 1.26 2.14 2.89 3.70 4.48 4.88 6.14 6.46 7.58cc-I 1.16cc-2 1.22 2.19 2.2cc-3 1.07 1.o9 2.63 3.32 4.01 5.30So-cc 1.20 2:06 2.82 7 4.48 5.09 6.14 6.46 7.58
SB-cc - Average of all results Closed Cham~ber cc-I - .089 g/co
SBR Strand Burner Closed Chamber cc-2 - .174 g/cc* erratic results Closed Chamber cc-3 - .258 g/cc
13
- i ~~.-. aZ-. - .
I
a
N .4 -' W 4 4 4 N
4 N 4 - 4 4 4 0 - 4 0 0 4
� 4 4 4 N - 0 4 4 4
4 - N 4 N 0 4
- N 4 4 � 4 4 4
- 4 4 4 � 4 N 0 0 4 - *- �
4 0 N 4 4 0 4 0 4 - � 4 4- - - N * 4 4 4 N 4 *A� 4
- - N 4 4 4 4 4 - *, .4 C - -I
- 4 N N 4 N 4 N - 4 0 0 40 a4J a
- - ft N N -, ..
- - N ) 4 * fl
4 - N N - 4 4 4 4 4 4 4 4
3444� - - - -
0- a 4 N 4 4 4 � 4 4 W 4 4 4
- N 4 4 - � 4 4 0 4 � 4 400. � - - N 4 4 4 N 4 4 -
0
0. - N - N 4 - 4 4 4 4 - I'. ft
* - - - *4 *4
- a 4 4 W 4 4 4 N 4 4 4 N N -f 4 4 - 4 4 - 4 4 N * 4 4
0 - N 4 4 4 N * 0 -- I-
.0 - N 4 N 4 4 4 N 4 4 4 * 4
X - - - N N 4 4 4
4 4 4 N 4 0 N 4 * 4 *6' N 4 4 4 4
- - Vt
4 4 4 4 4 N 4 4 - 0 4 4 4* 4 4 4 4 4 4 4 4 4 0 4 * Vt
�
14
E Table III. High Pressure Strand Burner Data
Burning Rate Burning RatePropellant Pressure Measured Calculated
Iea K[ai rn/s in./s =/s in./s
T465 (1l) 379 55 149 5.88 155 6.12448 65 177 6.97 182 7.17544 79 212 8.33 219 8.63621 90 271 10.67 248 9.77
T466 (fi) 193 28 184 3.30' 82 3.22
276 40 121 4.76 115 4.52283 41 126 4.98 117 4.62
379 55 165 6.50 155 6.12
469 68 218 8.57 190 7.49586 85 282 11.11 235 9.26
T467 (M2) 172 25 145 5.70 171 6.74
303 44 284 11.19 290 11.42
434 63 381 I.00 406 15.97517 75 435 17.14 426 16.79579 84 476 18.75 531 20.89
T468 (M2) 138 20 132 5.21 139 5.48
283 41 264 10.39 272 10.70414 60 368 14.50 386 15.21483 70 417 16.40 448 17.62
T470 (15) 138 20 134 5.27 130 5.13
283 41 257 10.12 257 10.13414 60 343 13.50 369 14.54414 60 353 13.90 369 14.54
*The burning rates were calculated using the bpn equations in Table IV.
15
r- a+bpn or r-bpn
a+bp bp
a + bp 9 0 bp*90
a + bp*8a bp*85
.80 80a + bp bp
Some form of the equations cited above is often used in simplifiedinterior ballistic calculation schemes. The least square fits of theabove data to the various specific equations were computed. The resultsare tabulated in Tables IVA and IVB.
When the coefficients for the various experiments are plotted•1 against the adiabatic flame temperature of the propellant (T) as shown
in Figures 1A and 1B, it is seen that the lines cross the temperatureaxis at 1800K. This suggests an analytical expression for the coefficientb as a function of flame temperature and exponent as shown below:
b = (T - 1800) (1.65 x 10- 7) (n 9.4); r - in./s, p - psi
b = (T - 1800) (4.19 x 10-7) (1 4 5 n) (n- 9 .4 ); r=- mm/s, p - MPa
V. PREVIOUS TEST IN CLOSED CHAMBER AT BRL
A series of 15 lots of Army propellants were fired in a 181 ccDupont Closed Chamber in 1951 at BRL. The chamber was 12 cm (4.72 in.)long and was 4.45 cm (1.75 in.) in diameter. The propellants weresingle perforated grains, 7-perforated grains and sheets of Ml, M2, M6,M1S and M8 composition. These propellants are described in Table V.
Figures 2 through 8 compare these burning rates with the previouslydescribed re-extruded standards. The slight disagreement is attributedto small differences in composition. The data plotted on these figuresinclude each of the standard propellants shown in Table II. The lineshown is the least square fit of only the closed chamber data. Thepoints within the square symbols are the best fit to the equationr = bpn for the combined data shown in Table IV. Since only the standardpropellant data are available, the figures for the MS and MlO propellantsare presented for information only.
VI. BURNING RATE DATA FROM OTHER AGENCIES
I. During the first quarter of the 20th century, many European agenciesconducted burning rate experiments which are summarized in Section 18 of
16
Table IVA. Least Square Parameters for Various Burning Rate EquationsUsing Combined Strand Burner and Closed Chamber Results
Standard ArmyPpel latot Lo vi M2 MS N6 Ni MlO N17
r sabp a .122 .288 .475 -. 048 .015 .082 .272b 0 .834 2.29 .338 2.87 11.5 2.38 3.383 1.027 1.011 1.100 .924 .'878 .955 .930a .01S8 .143 .373 .0167 .0815 .0721 .129
a~bp a .050 .242 .060 .129 .800 .19 .483b z 10 1.131 2.572 2.S15 1.247 2.968 1.458 1.$639 .0173 .145 .470 .056 .227 .080 .141
"a~bp"95 a -. 062 -. 013 -.189 .019 .499 .046 .278b 1 10 1:964 4.47 4.369 2.182 S.170 2.533 2.7159 .02S0 .419 .548 .051 .134 .0702 .153
a*bp"90 a -. 187 -. 298 -. 467 -. 116 .169 -. 115 .SSb x 10 3.420 7.78 7.609 3.800 9.003 4.420 4.729r .0429 .243 .706 .053 .089 .0738 .132
a4bp"85 a -. 447 -. 89 -1.046 -. 400 -. S3S -. 450 .. 20Sb x 10 6.153 14.00 13.69 6.836 16.199 7.94 8.519 .0883 .471 1.020 .092 .249 .127 .198
a&bp"0 a 4 -. S13 -1.042 -1.19S -. 473 -. 691 -. 537 -. 297b x 10 10.!4 23.97 23.44 11.70 27.736 13.S9 14.57C .0979 .505 1.103 .294 .161 .119 .185
bpn b x 104 1.90 5.316 4.293 2.20 12.00 3.46 9.41ft .951 .933 .948 .949 .874 .921 .836€ .0361 .152 .661 .027 .085 .076 .173
bp b x 104 1,146 2.68 2.648 1.280 3.226 1.SIS 1.715C .212 .260 1.42 .C68 1.447 .512 .608
bp.95 b x 104 1.931 4.46 4.266 2.16 5.44 2.557 2.890. .0448 .181 .617 .0185 .S79 .0746 .A34
90 4bp' b x 10 3.249 7.508 7.179 3.630 9.1S7 4.305 4.868E .2305 .386 .982 .037 1.139 .094 .179
bp'85 b x 10 5.461 12.62 12.06 6.102 15.402 7.238 3.189.4677 .904 1.73 .1311 .IS2 .220 .148
.80 4bp b x 10 9.347 21.27 20.32 10.282 25.961 12.195 13.80SS 1.357 1.778 2.72 .309 .679 .467 .259
Units r in./$c = Z (r - r
C 0a in./sb n'//(psi)n rc - calculated
re experimcntal
17
fl
Table IVB. Least Square Parameters for Various Burning Rate EquationsUsing Combined Strand Burner and Closed Chamber Results
Propellant Type I Ii S 116 M5 M M10 M17
t - a+bp a 3.099 7.315 12.065 -1.219 .381 2.083 6.909
b .351 .891 .508 .724 2.308 .701 .879"n 1.027 1.011 1.100 .924 .878 .955 .930
a+bp a 1.270 6.147 1.524 3.276 20.320 4.826 12.268b .417 .947 .926 .459 1.093 .537 .576
+bP -. 574 -3.302 -4.801 .482 12.675 1.168 7.061"b .544 1.284 1.255 .627 1.485 .727 .780
a4bp"90 a -4,750 -7.569 -11.862 -2.946 4.292 -2.921 3.937S5 b .766 1.742 1.704 .851 2.016 .990 1.059
aabP a -11,353 -22.606 -26.568 -10.160 -13.001 -11.430 -5.207b 1.074 2.444 2.390 1.193 2.828 1.386 1.486
a&bp"80 a -13.030 -26.466 -30.353 -12.014 -17.551 -13.640 -7.544b 1.435 3.263 3.191 1.593 3.781 1.850 1.983
bpn b .548 1.403 1.221 .629 2.361 .860 1.532"n .951 .933 .948 .949 .874 .921 .836
bp b .422 .987 .975 .471 1.186 .559 .632
bp" b .554 1.281 1.225 .620 1.562 .734 .830
bp"9 b .727 1.681 1.607 .812 2.050 .964 1.090
bp"85 b .953 2.203 2.105 1.065 2.689 1.264 1.430
bp"80 b 1.272 2.895 2.766 1.400 3.534 1.660 1.879
UnIts r mm/sa run/sb mm/s/(Mpa)n
18
GROLLMAN 1976 1955 DATA
i/js b (T-1800) (1.66 x 10-7 &-9.4)
pn b- r/pn
.0030 T- Kelvinp" psir- ia/s
.0025 a: .8
- .oi-t -8u
.020 Xx
U
L& 0 nz.85
I. X
S.001n .9
U
.0005 - x.9XXx
01500 2000 2500 3000 3500 4000
TEMPERATURE °K
S~Figure lA. Correlation of Burning Rate Coefficient with Flame Temperature
'• 19
.0005 - x
b z(T -1800) (4.13 x 1061) (14 )n- 9 4
r = bpn r = mm/s
p: MPGmm/s
(MPo)nT= Kelvin
MM/S
MPOn5
nz.I.-
U-
'LU0U
<2x x n- 95
z ,x n =I.0z fl:1
x x
1500 2000 2500 3000 3500 4000
TEMPERATURE *K
Figure lB. Correlation of Burning Rate Coefficient with Flame Temperature
20
----------------
S•me . •
•.. .•.. o4oo oo
0 • .. '. .
• ... . N. - •. . .
odo .3~~ 8 C"!AIUW
; .C. . ... '
.*- *. U- : " :-_ " - : _- ~. * O 0
g, z~ -'-4 ft. 0 0
o - o . . . . ..-.
4-4
*.. . . . . . . . . . . . . . . . . 4 -
0 21 9n ... ~go a
Ont-N0
-4!
* ~ ~ ~ ~ C a~;g~'4.-.44 ~I.; n;* o d
* pM.4 A
w z a-'Z,10
z~ o.~ ~21
STRAND BURNER T-466+ STRAND BURNER T-465o CLOSED CHAMBER0 BEST COMBINED FIT
in. mm-1 6658 SP .0146 .371-2 10793 SP .0234 .594
mm/s ill/s -3X5677 MP .0238 .605
50. 20
250- 10-
5100-
2.5-u 50"
-3
21z 0D 22
.25
5- .251 /
x
2 .5 - .1 - , I I I I . * , i i ksi5 1 2 3 4 5 8 10 20 50' " I -.. I I . . L MPG
3 5 10 20 30 4050 100 200 400PRESSURE
Figure 2. Burning Rate Comparison for Ml
"22
I
STRAND BURNER T-468+ STRAND BURNER T-467o CLOSED CHAMBER0 BEST COMBINED FIT
in. mm-1 12585 SP .0148 .376-2 302 SP .0214 .544
mm/s in/S -3 5316 SP .0301 .765
50 20 -4 5280 MP .0402 1.021
-5 4582 MP .0852 2.164 ,
250 10
-3
100. 2-
2.5"l u 50-4
2 25- 1.0-
+
.5-10-
5-
.1. 1 f I I I I j I I ksi2.5 1 2 3 4 5 8 10 20 50
SI . .. I I I I t I I . . I , I I * L " M Po3 5 10 20 30 4050 100 200 400
PRESSURE
Figure 3. Burning Rate Comparison for M2
23
ILa
mm/s in/s x STRAND BURNER T-47050. 20- + STRAND BURNER T-469
o CLOSED CHAMBER2 BEST COMBINED FIT
250 10-
5100
2 5-
5-
"5 1 2 3 4 5 8 10 20 50
3 5 10 20 30 40 50 100 200 400PRESSURE
Figure 4. Burning Rote Comparison for M5
Figure 4. Burning Rate Comparison for M5
24
x STRAND BURNER T-472+ STRAND BURNER T-471
o CLOSED CHAMBERin BEST COMBINED FIT
ft. mm
-1 3727 SP .0126 .320
-2 6526 MP .0258 .655
5 20. -3 14085 MP .0376 .955502
250 10
100-
2.5"tu50-
25 1.01,23
3 0o
.5-30
-
25
2 .i I I....I 1 I ksi2 5 1 2 3 4 5 8 10 20 50
I i . . . .I . I I I i .* * * I * I * I M P o3 5 10 20 30 4050 100 200 400
PRESSURE
Figure 5. Burning Rate Comparison for M6
IsI
.-. ,-
x STRAND BURNER T-474
+ STRAND BURNER T-473
o CLOSED CHAMBER0 BEST COMBINED FIT
in. mm
-1 9697 SHEET .0202 .513
-2 16395 SHEET .0235 .597mm/s in,/s -3 208 SHEET .0463 1.176
50- 2
250- 10 /
5-.3 \ -
100- -/ 32\2
25-12
Z 2
S25 1.0-
10
.25-5-
25 i I , *....I * I . ksi3 1 2 3 4 5 8 10 20 50
! - . * . I -I -- I I I . I I I M Po3 5 10 20 30 4050 100 200 400
PRESSUREFigure 6. Burning Rate Comparison for M8
26
1
STRAND BURNER
T-476
+ STRAND BURNER T-475
o CLOSED CHAMBER0 BFrST COMBINED FIT
mm/s in/S50- 20-
250" 10-
5-100o;
ulj50-
z225- 1.0-
.5.10-
.2.5-5-
2..5 1 t , I I I... . , I Ii5 1 2 3 4 5 8 10 20 50I I . .. . I I I I I . . . . I I - I M P G
3 5 10 20 30 4050 100 2CI 400PRESSURE
Figure 7. Burning Rate Comparison for MIO
27
-STRAND BURNER T-47-+ STRAND BURNER T-477
o CLOSED CHAMBERm BEST COMBINED FIT
in. h.om
-1 6298 CORD .014 .36.mi/s in/s
50 20
250- 10
5 /100-
soo-
2.s/
50 x
-25- 1.0-
5 0
10 - -'
.25-5.
2 .1 kI I . . . I , ,i.5 1 2 3 4 5 8 10 20 50
, I . . . . 1 1 1 I ! I" P..a
3 5 10 20 30 4050 100 200 400 MPRESSURE
F:igure R. Burning Rate Comparison for M17
28
Cranz, 1925. These rates for the NC propellant, which is similarto Ml progellant, were close to our measured values. In 1917, Col.Tschappat of the USA published the following:
The specific rate of combustion (k') is the regression normal tothe surface of the propellant burning in its own gas at a pressure ofone pound per square inch. It is proportional to the energy per poundof propellant (n') and is inversely proportional to the sum of thefollowing:
(1) The energy required to heat a pound of propellant to the
ignition temperature.
(2) The energy required to evaporate the water and alcohol fromthe propellant.
His equation (6) is
kf 9 .00000677n'87.5 (3569F - Temp of Prop) + 8400 (% H2 0) + 2080 (% alcohol)
The value of k' agrees with our presented coefficient for Ml.
He experimentally determined k' by placing several large grains ingun charges and measured the regressed distance in the recovered grains.His equation (9) was used to calculate the value of k' and it agreed forthe several weapons tested. Then he determined the coefficients in theprevious equation (6).
II. Geckler has a thorough treatment of combustion 7. He tabulated thedata of several investigators, and the results of Muraour are ofparticular interest. Both strand burner and closed chamber resultsare shown but unfortunately are not for identical propellants. Theequations in section 2.4 relating the burning rate coefficients to theflame temperature of the propellants provide a very good fit to the datapresented in Table II.
These equations are
r = 0.2 + O. 0 0 0 0 2 1 2 e' 7 09 (T/1000)p; r - in./s, p -psi
r = 5.0 + 0.078e' 7 09 (T/'lOOO)p; r = mim/s, p - MPa
5C. Crana, "Lehrbuch der Ballistik," Bd II, Innere Ballistik, Sp2inger,Berlin, 1926, translated NDRC, 1945.
6W. H. Tachappat, "Text Book of Ordnance and Gunnery," Wiley, New York,
1917.
?R. D. Gecklar, "Selected Combustion Problems," AGARD, "The Mechanismsof Combustion of Solid Propellants," Butterworths, London 1954, pp.289-299.
29
III. The composition of small arms propellants varies during burningas a result of the change in concentration of nitroglycerin (NG),nitrocellulose (NC) and the deterrent coating dibutylphthalate (DBP).As a consequence, BRL had a contract with Olin Corporation in 1974 toconduct closed chamber firings to provide8 burning rates for the interiorballistic prediction codes for small arms . The work included manufacturing16 lots of propellant in two web sizes with 0 or 10% NG and with 0, 5,10 and 15% DBP. Five samples of each propellant composition were burnedin a closed chamber at a density of loading calculated to achieve a noheat loss maximum pressure of 180 HPa (26,000 psi). The smaller webfor each propellant was also burned at 60% and 80% of the full charge.The raw data are reported as well as the calculated burning rates.Chemical analyses and thermochemical properties of all the propellantsare tabulated in the Olin Corporation report.
The data for all the full charge firings were combined to obtain the
linear burning rate constants as functions of propellant composition.
r = bpn
loger log eb + n log ep
logeb - A° + A1 (% DBP) + A2 (% NG) + A4 (web) 2
n = no = nI (% DBP) + n 2 (% NG) + n 3 (web) + n 4 (web) 2
The web effect was very small and the following coefficients andexponents best fit the data:
r (in./s), p (psi) r (mm/s), p (MPa)
Constant Coefficient b = 9.833 x 10-4 b - 0.0250(145)n
n0 0.83881 0.838810
nI 2 0.00S81 0.00581
n2 0.00175 0.00175
Constant Exponent A = 6.61822 0.62429
A1 =-0.052882 -0.052882
A = 0.015907 0.015907
n = 0.80530 0.80530
8 D. W. Hiefler, "Linear Burn Rates of BaZl Propellants Based on Closed
Bomb Firings," BRL CR 172, Olin Corporation, Aug 1974. (AD #921704L)
30
The Olin constant exponent equation fits the BRL data very well; eventhough the BRL M8 composition has four times the NG content of thattested by Olin and the pressure levels were approximately twice thatobtained by Olin.
VII. CONCLUSIONS
1. The burning rates calculated from strand burner and closed chamberdata agree for identical propellants; however, the burning rates can bealtered due to lot-to-lot variations in propellant ingredients.
2. The burning rate coefficient and exponent can be correlated to thecalculated adiabatic flame temperature for the various types of
* propellant.
3. The burning rate coefficient and exponent are not independent.
31
4 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
REFERENCES
1. F. C. Kracek, "Hypervelocity Guns and the Control of Gun Erosion,"Part II Ballistics, Chapter 2, NDRC, Washington,-D. C., 1946, pp. 21-53.
2. R. H. Kent, "Report on Determination of Interior Ballistic Databy Closed Chamber Experiments in Connection with Project RB158,"
- BRLR 32, Jan 1936.
3. R. H. Kent, J. P. Vinti, "Cooling Corrections for Closed Chamber* Firings," BRLR 281, Sep 1942. (AD #491852)
4. J. H. Wiegand, "A Method for the Calculation of the Burning Rate ofPowders from dp/dt Records for Closed Chambers," BRLR 546, May 1945.
S. C. Cranz, "Lehrbuch der Ballistik," Bd II, Innere Ballistik, Springer,Berlin, 1926, translated NDRC, 1945.
6. W. H. Tschappat, "Text Book of Ordnance and Gunnery," Wiley, NewYork, 1917.
7. R. D. Geckler, "Selected Combustion Problems," AGARD, "TheMechanisms of Combustion of Solid Propellants," Butterworths, London,1954, pp. 289-299.
8. D. W. Riefler, "Linear Burn Rates of Ball Propellants Based on ClosedBomb Firings," BRL CR 172, Olin Corporation, Aug 1974. (AD #921704L)
33
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