Propagation of Detonation Wave

Examining the conditions for the formation and propagation of detonation waves is relevant to special applications of detonations to propulsion as well as safety. 

The propagation of detonation wave in the explosive was observed by means of flash-radiography. It was possible also to compare, in some cases, the pressure exerted on the confining Perspex walls as a function of the priming of the chge by photographing the shock wave in a Perspex block (Ref 7)... 

ZhEksp i Teoret Fiz 12 389 (1942) (Pressure and velocity distribution in detonation products of an explosion specifically for spherical propagation of detonation wave)... 

Velocity of detonation dependent on diameter of explosive charge, i.e. critical diameter Does not usually revert to deflagration, if propagation of detonation wave fails explosive composition remains chemically unchanged... 

On initiating by a No 8 blasting cap, check the propagation of detonating wave between the two lengths... 

Detonation of Condensed Explosives by Roger Cheret published by Springer-Verlag in 1993 is the outstanding detonation physics text of the century. Cheret describes the mechanical and thermodynamic aspects of the propagation of detonation waves, the molecular and macroscopic mechanisms of explosive decomposition, and the dynamic characterization of explosives. 

This reaction can oscillate in a well-mixed system. In a quiescent system, diffusion-limited spatial patterns can develop, but these violate the assumption of perfect mixing that is made in this chapter. A well-known chemical oscillator that also develops complex spatial patterns is the Belousov-Zhabotinsky or BZ reaction. Flame fronts and detonations are other batch reactions that violate the assumption of perfect mixing. Their analysis requires treatment of mass or thermal diffusion or the propagation of shock waves. Such reactions are briefly touched upon in Chapter 11 but, by and large, are beyond the scope of this book. 

For very rough tubes, the flame acceleration is much more rapid as shown in the previous section. Transition to detonation is also clearly marked by a local explosion and abrupt change in the wave speed. The wall roughness controls the propagation of the wave by providing [5] ... 

Some relations characteristic of the unidimensional steady propagation of deton and normal burning are given with special ref to the physical proof of the Chapman rule of the minimum vel in the deton wave... 

C.G. Dunkle, in his Syllabus (Addnl Ref E) describes Propagation of Detonation in Air Blasts (pp 313-15), Mach Waves (pp 315-17) and Blast Effects in Water and Earth (pp 317-18). In his private communication (Ref G), he suggests including the following ... 

W.A. Gey M.A. Cook (Ref 4). Their experiments in propagation of deton thru steel glass plates showed that thin plates of inert material invariably interrupt the deton wave completely, requiring the deton to re-form if it continues to propagate beyond the interrupter. A remarkable "new phenomenon, called flash-across, was observed when a bluish-white hot spot on one frame and another hot spot that developed between adjacent frames on the opposite SPHF plate had both flashed across the chge and met at the collision interface... 

CA 27, 5979(1933) (A detonating cap was placed in a lead cylinder and axially under this, and at definite distance, a 2nd cap was fixed. When the 1st cap exploded the deton wave traveled thru the air to the 2nd cap whose expln made an impression in the Pb cylinder. By changing the distance betw the caps, a value for the sensitiveness to propagation of deton was obtd) 9) D.B. Gawthrop, JFrankllnst 214, 647(1932) (Deton by influence) 10) R.L. Clark, IEC 25, 663-67(1933) (Deton by influence)... 

SocJ 30, 151-58(1960) (Recent advances in condensed media detonation) 37b) Dunkle s Syllabus (1960-1961), pp 4a 4b (Initiation of shock waves) lOa-lOg (Initiation of deflgrn and deton) p 12a (Frank-Kamenet-skii formulation) p 13b (Initiation by electric discharge) p 13f (Thermal Decomposition and Initiation of Explosives, as discussed by B. Reitzner) pp 17a to 17e (Mechanism of initiation and propagation of detonation in solid explosives) pp 17e 17f [Marlow Skidmore (Ref 31) concluded from their investigations that the problem of shock initiation is somehow related to the temperature distribution in the shock pulse and its effect on the chemical reaction rate. They used an Arrhenius type relationship for the rate increase in the frac-... 

Expansion of the expln products in the forward direction in a cylinder is accompanied by compression of new layers previously undisturbed in the xplosion and this causes some loss of energy, which is considered, however, not as a loss, but as a normal part of the detonation process. Expansion of the expln products in the rearward direction proceeds more slowly as the path traversed by the wave in the explosive becomes greater, i.e., the thicker the layer of compressed expln products behind the wave becomes, the more slowly the expansion proceeds. Thus for a large chge diam, the more powerful is the initiator causing the initial wave, the smaller are the losses at the origin of propagation of detonation. 

As the wave evolves from that point, the losses connected with rearward expansion decrease. If a charge of a small diam is considered, then lateral expansion depends on the path over which the wave has traveled. The increase in cross section of a cylinder, i.e., expansion in the lateral direction, leads to a reduction in pressure and to a decrease in the deton velocity in comparison with detonation propagating in a constant cross-section cylinder. The decrease in deton vel causes, in turn, the diminution of shock amplitude wave and impairs the conditions under which the reaction can proceed. The loss caused by lateral expansion is known as lateral loss. Propagation of detonation is possible only if this loss is not smaller than a certain limit, which is characteristic for each expl... 

For powders, such as Lead Azide (LA), the limiting diam is small and it is possible to have conditions such that each particle of the powder taken separately is able to detonate. In this case the deton wave being propagated represents an aggregate of deton waves being propagated in separate crysts and which are transmitted from one cryst to the next... 

Refs 1) Ya.B. Zel dovich, ZhEksper i TeoretFiz 10, 542(1940) (On the theory of propagation of detonation in gaseous systems) la) J.G. Kirkwood S.R. Brinkley Jr, "Theory of Propagation of Shock Waves from Explosive Sources in Air and Water , OSRD 4814(1946) 2) G.N. Abramovich ... 

Detonation, Strain Waves in Rock. Such waves are described under the title Generation and Propagation of Strain Waves in Rock ,... 

---