Explosion, spherical

Detonation, Point Initiation of. See under DETONATION (AND EXPLOSION) SPHERICAL... 

Field Behind a Spherical Detonation in TNT Using the Landau—Stanyukovich Equation of State for Detonation Products [See also under Detonation (and Explosion), Spherical and under Detonation, Spherical Wave for the Gaseous Products of Solid Explosives in]... 

J. M. Goldman and E. H. Zeigler, Jr., "The Shock Nitration Process for Spherical Propellant Manufacture," in Symposium on Processing Propellants, Explosives, and Ingredients, ADPA, Washington, D.C., 1977, p. 23. 

Criticality Precautions. The presence of a critical mass of Pu ia a container can result ia a fission chain reaction. Lethal amounts of gamma and neutron radiation are emitted, and a large amount of heat is produced. The assembly can simmer near critical or can make repeated critical excursions. The generation of heat results eventually ia an explosion which destroys the assembly. The quantity of Pu required for a critical mass depends on several factors the form and concentration of the Pu, the geometry of the system, the presence of moderators (water, hydrogen-rich compounds such as polyethylene, cadmium, etc), the proximity of neutron reflectors, the presence of nuclear poisons, and the potential iateraction with neighboring fissile systems (188). As Httle as 509 g of Pu(N02)4 solution at a concentration Pu of 33 g/L ia a spherical container, reflected by an infinite amount of water, is a critical mass (189,190). Evaluation of criticaUty controls is available (32,190). 

Fig. 9.1-5 Shock Wave Parameters fora Spherical TNT Surface Explosion at Sea level.

The upper half of Figure 3.9 represents how a spherical explosive charge of diameter d produces a blast wave of side-on peak overpressure P and positive-phase duration r" " at a distance R from the charge center. Experimental observations show that an explosive charge of diameter Kd produces a blast wave of identical side-on peak overpressure p and positive-phase duration Kt at a distance KR from the charge center. (This situation is represented in the lower half of Figure 3.9.) Consequently,... 

Analytical methods relate the gas dynamics of the expansion flow field to an energy addition that is fully prescribed. A first step in this approach is to examine spherical geometry as the simplest in which a gas explosion manifests itself. The gas dynamics of a spherical flow field is described by the conservation equations for mass, momentum, and energy ... 

The very first stage of flame propagation upon ignition, during which the flame has a spherical shape, mainly determines the blast peak overpressure produced by the entire vapor cloud explosion. 

In Figure 6.16, the region originally occupied by the gas cloud is shaded, and the position and shape of the shock wave and the contact surface at different times following the explosion are shown as solid and dashed curves. The shape of the shock wave is almost elliptical, with ellipticity decaying to sphericity as the shock gradually degenerates into an acoustic wave. 

The above procedure produces blast parameters applicable to a completely symmetrical blast wave, such as would result from the explosion of a hemispherical vessel placed directly on the ground. In practice, vessels are either spherical or cylindrical, and placed at some height above the ground. This influences blast parameters. To adjust for these geometry effects, and 7 are multiplied by some adjustment factors derived from experiments with high-explosive charges of various shapes. 

The factors tliat affect miconfined I apor cloud explosions me not well understood. In a model developed by William, it is assmned tliat ignition occurs at a point source, tliat tlie flame front travels out from tlie core at a flame speed S, and tliat the pressure waves produced by the flame generate a weak shock wave tliat travels ahead of tlie flame with a time-dependent velocity. Tlie equation for the flame speed for spherical systems is... 

Table 7-26 [49] has been developed by ratio of relative heats of explosion. For close explosion, i.e., (Z < 3.0 ft./lb / ) and for shapes other than spherical, the TNT equivalent factor can be much greater than those from relative heats of explosion [49]. 

E = Joint efficiency in cylindrical or spherical shells or ligaments between openings (see ASME Code Par.lJW-12 or UG-53) e = natural logarithm base, e = 2.718 e, = TNT equivalent (explosion) (see Table 7-26)... 

The first offensive weapons used by man were probably stones, and similarly the first objects thrown when mortars were developed were solid, usually spherical, balls of stone or iron. With the development of explosives it was soon realised that it would be more effective to use a hollow missile filled with explosive, designed to burst in the middle of the enemy. Gunpowder was originally used as filling, but has now been completely superseded by high explosives. 

An unknown event disturbed the equilibrium of the interstellar cloud, and it collapsed. This process may have been caused by shock waves from a supernova explosion, or by a density wave of a spiral arm of the galaxy. The gas molecules and the particles were compressed, and with increasing compression, both temperature and pressure increased. It is possible that the centrifugal forces due to the rotation of the system prevented a spherical contraction. The result was a relatively flat, rotating disc of matter, in the centre of which was the primeval sun. Analogues of the early solar system, i.e., protoplanetary discs, have been identified from the radiation emitted by T Tauri stars (Koerner, 1997). 

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