Page 24 - 《含能材料》2018年优秀论文

690 FENG Song，RAO Guo‑ning，PENG Jin‑hua

an underwater explosion event take place over a Table 2 Results of shock energy，gas bubble and total energy
much larger time than of the shock wave. The bub‑ θ
sample pm Tb es eb et
ble energy released by explosives explosion is relat‑ / MPa / μs / ms /MJ·kg -1 /MJ·kg -1 /MJ·kg -1
ed to the period of the first bubble oscillation. The 1 # 15.52 20.58 46.75 1.13 2.24 5.74
equation used in calculating the specific bubble en‑ 2 # 15.49 20.63 46.76 1.13 2.24 5.74

ergy is expressed as follows： 3 # 15.20 22.34 49.97 1.31 2.96 7.02
3 #
é 5 ù 4 15.12 22.56 50.43 1.31 3.01 7.06
1 ê ê ( ) 6 ú
p h
E b = 3 ê ê 1 + 4Ct b - 1 ú ú （6） that addition of aluminum powder is of advantage to
3
8C K 1 ê ê p hn ú
ë û increase the underwater explosion energy such as
E - E' - E ″ shock energy，gas bubble and total energy. The time
e = b W b b （7） constant θ of CL ‑ 20 ‑ based aluminized explosive is
b
Where C and K are constants at a given charge larger than that of CL‑20‑based explosive. The bub‑
1
location in a given pond，t is the first bubble peri‑ ble pulse period increases by about 7.4%. The shock
b
od， s； p h is the total hydrostatic pressure at the wave energy of the CL‑20 ‑based aluminized explo‑
charge depth（including atmospheric pressure），Pa； sive is 1.31 MJ·kg ，and it is 1.16 times larger than
-1
as normalization pressure p hn should use a pressure CL ‑ 20 ‑ based explosive. The bubble energy of the
given by the sum of the normal atmospheric pressure CL ‑ 20 ‑ based aluminized explosive is 33.3% higher
at the surface of the pond（for example 101325 Pa than CL‑20‑based explosive. These are signs that alu‑
for a sea level site） and the hydrostatic pressure at minum powder can greatly improve the bubble ener‑
the chosen charge depth，Pa；E is the gas bubble gy. The total energy measured at measuring point of
b
energy at measuring point，J；E′ denotes the gas CL‑20‑based aluminized explosive increases by about
b
bubble energy by booster charges at measuring 27.4%. The total underwater explosion energy per
point，J；E″ is the gas bubble energy by No. 26 electric mass unit of an explosive e approaches heat of deto‑
b
t
detonator at measuring point，J；e denotes the gas nation of the explosives ［26］ . The heat of detonation of
b
bubble energy per kg explosives at measuring the CL‑20‑based explosive is 5.95 MJ · kg -1［39］ . The
point，J · kg ；W denotes the charge weight of ex‑ total underwater explosion energy of CL‑20‑based ex‑
-1
plosive ，kg. plosive is 5.74 MJ · kg ，and it is 1.4 times larger
-1
3.3.3 Specific Total Energy than TNT （4.09 MJ · kg ） in underwater explosion
-1
) ［40］
e t = K f (μe s + e b （8） energy . Compared with the heat of detonation of
Where e is the total underwater explosion ener‑ the CL‑20‑based explosive，the error is about 3.5%.
t
gy per mass unit of an explosive，J · kg ；K is the The total underwater explosion energy e increases
-1
t
f
charge geometry factor，for cylinder shaped charge， by 22.6% with addition of aluminum powder in
K =1.08-1.10；µ is the shock loss factor，only re‑ CL ‑ 20. The total underwater explosion energy of
f
lates to the detonation pressure of explosives；More CL‑20‑based aluminized explosive is 1.7 times larger
details about these equations can be found in Bjarn‑ than TNT. But beyond that，the peak pressure in pri‑
holt ［26］ . In order to get accurate results，a blank test mary shock wave decreases slightly for CL ‑ 20 ‑ based
must be conducted only including No. 26 electric aluminized explosive. So the addition of aluminum
detonator and booster charges. powder can attain the purpose to increase time con‑
According to the pressure histories of shock stant，bubble pulse period and explosion energy. Be‑
wave in Fig.3 and Eqs.（1）-（8） ［26］ ，the shock ener‑ cause aluminum can react with explosion products to
gy，gas energy and total energy of the explosives give out a lot of heat and gas，decay of pressure slows
can be calculated，as shown in Table 2. It is obvious down and shock energy and total energy increase as

Chinese Journal of Energetic Materials，Vol.26, No.8 , 2018（686-695） 含能材料 www.energetic-materials.org.cn