CHAPTER 22 MODELING AND UNDERSTANDING BLEVEs

22.24 CHAPTER TWENTY-TWO
On a vertical surface,
And on a horizontal surface,
�2
I � � � F � Ep � 0.69 � 0.24 � 266 � 44 kW � m
�2
Iv � I � cos � � 44 � 0.68 � 30 kW � m
�2
Ih � I � sin � � 44 � 0.73 � 32.3 kW � m .
2. Estimation of pressure wave
The overpressure is estimated from Eqs. (22.20), (22.21), and (22.22):
ƒ � 1 � e
22.7 NOMENCLATURE
(�2.63�C /H �( T �T )�(1�(T �T / T �T ) 0.38
p v c b c o c b ))
(�2.63�(2.4�10 3/4.3�10 5)�(369.8�231.1)�(1�((369.8�328)/(369.8�231.1)) 0.38))
� 1 � e � 0.525
��
� 444
l 3
V* � V � Vl � ƒ � � 50 � 200 � 0.525 � � 1310 m
� 37
v
(��1)/�
0.021 PV* Pa 0.021 � 19 � 1310
� � � � � �
� �
(1.14�l)/1.14
1 � � � �
WTNT � � 1 � �
� � 1 P 1.14 � 1
� 1 � � 1133 kg
19
admitting that 40% of the released mechanical energy is transformed in pressure wave
(ductile breaking of the vessel):
d n is calculated with Eq. (22.23):
(W ) � � � W � 0, 4 � 1133 � 453 kg
TNT overpressure TNT
d 180 �1/3
dn � � � 23.4 m � kg
1/3 1/3
(� � W ) 453
TNT
With the TNT equivalence diagram (overpressure versus d n, Fig. 22.3), an overpressure
of 0.05 bar is found.
A Constant in the Antoine equation (–); in Eqs. (22.28) and (22.29) bore cross-section
area (m2 )
a Constant (�)
Sound velocity in the vapor (m � s�1 )
Velocity of flow at exit plane (m � s�1 )
ao am aw propagation velocity of the initial rarefaction wave (m � s �1 )
B Constant in the Antoine equation (�)
b Constant (�)
c Constant (�)
C p
Specific heat at constant pressure (J � kg �1 � K �1 )
D Diameter of fireball (m)
d Distance from the center of the vessel to the point at which the overpressure must
be calculated (m)