Environmental Engineering Reference
In-Depth Information
Here, u
m
is the mass burning rate with unit g/cm
2
s;
a
k
is the surface tension of a
q
1
is the density (g/cm
3
) of gas productions;
liquid and its saturated vapor;
d
1
is the
density of a liquid explosive.
According to
d
l
values from experiments, the calculated mass
burning rates u
m
of methyl nitrite, diethyleneglycol dinitrate, and nitroglycerine in
one standard atmosphere press are 0.25, 0.26, and 0.25 g/cm
2
s, separately. It is
concluded that the right side of Eq.
2.19
is approximated as a constant. If the
pressure is 1 atm, it is 0.25 g/cm
2
s. When the burning rate is over 0.25 g/cm
2
s,
detonation of liquid explosives is possible.
If the impact of liquid viscosity is considered, the normal burning limit rate is
Eq.
2.20
.
a
k
; q
1
;
and
1
=
3
3
p
g
lq
3
=
2
1
=
2
u
m
¼
d
ð
2
:
20
Þ
2
l
Here, u
m
is the mass burning rate (g/cm
2
s) with impact of liquid viscosity;
l
is
q
2
is the density (g/cm
3
) of gas productions;
the viscosity of a liquid (poise);
d
1
is
the density of a liquid explosive.
If the detailed burning study of nitrate ether is planned, the impact of liquid
viscosity should be in consideration. The viscosity of nitroglycerine is 0.36 Poise.
When
6g
cm
3
, the calculated limit rate is
0.17 g/cm
2
s. The experiment rate is 0.28 g/cm
2
s. The viscosity of nitroglycerine
could not guarantee the stable burning. If the above values of gas production and
liquid explosive are applied, stable burning is guaranteed only when the viscosity of
nitroglycerine is larger than 1 poise. Plastic process of nitroglycerine enlarges the
viscosity, so plastic nitroglycerine has stable burning. Experiments proved that the
burning of mixtures of nitroglycerine and colloxylin (99:1) is unsteady before
colloxylin becomes colloidal. After colloxylin becomes colloidal, the viscosity of
mixtures of nitroglycerine and colloxylin (99:1) increases to 3.5 Poise. According
to the viscosity, the burning limit rate is 0.37 g/cm
2
s. So the colloidal has a stable
burning rate of 0.24 g/cm
2
s.
Pressure boot greatly impacts the viscosity of stable burning guarantee. At 1 atm,
the required viscosity is
10
4
g
cm
3
q
2
¼
:
d
1
¼
:
1
72
and
1
1 Poise. The required viscosity increases dramatically
when pressure is boosted. For example, the required viscosity at 100 kg/cm
2
*
is
1,000 times of that at 1 atm.
2.2.1.6 Burning/Combustion to Detonation of Liquid Explosives
Burning/combustion and detonation are two different concepts, but they intercon-
nect with each other. Breaking the stable burning/combustion of explosives may
lead to detonation.
When the products of liquid explosive burning reaction do not diffuse well, the
reaction surface increases and the burning rate also accelerates. Once the critical value
