Gurney constants, explosives

Initial velocities of explosively driven metal fragments can be accurately estimated by the so-called Gurney formula (see Vol 6, G195-R). The writer (Ref 81a) used the Ref 45 data referred to above to compute a Gurney constant /2E1 (for tangential detonation) of 3.04mm/ psec for 1.765g/cc PETN... 

Another Dupont sheet explosive is EL506D. It contains about 70% PETN and has a density of 1.4g/cc. Gurney constants for it are 2.50mm/ psec (Roth, Ref 81a) and 2.28mm/psec (Kennedy, Ref 88, p 117)... 

The conditions of the charge detonation in metal cylinders, i.e., warheads, are well described by Eq. (5.39). From this equation, it can be seen that the wall velocity during expansion depends on the ratio between the masses of the cylinder and the explosive. The quantity yj2Ef, is called the Gurney constant. 

The constant JlE is the so-called Gurney velocity (in km s ), which is dependent on the nature of the explosive. 

Figure 7.21 also shows that the Gurney velocity for a specific explosive, with a particular charge density, is only constant when the surface density (in g cm 3) of the cylinder walls is above a critical value of approx. 1 g cm 2. 

If an explosive charge detonates in a metal cylinder, and assuming that the density of detonation products is constant, the Gurney ener Eg) can be expressed by the equation... 

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