Detonation transition from deflagration

If a large amount of a volatile flammable material is rapidly dispersed to the atmo vapor cloud forms. If this cloud is ignited before the cloud is diluted below its lower flammability limit, a UVCE occurs which can damage by overpressure or by thermal radiation. Rarely are UVCEs detonations it is believed that obstacles, turbulence, and possibly a critical cloud size are needed to transition from deflagration to detonation. 

Lee, J. H. S., and I. O. Moen. 1980. The mechanism of transition from deflagration to detonation in vapor cloud explosions. Prog. Energy Combust. Sci. 6 359-389. 

Macek (Ref 5) used Pentolite (and DINA) to study the transition from deflagration to detonation (DDT). He found that in Pentolite,... 

See Vol 3 of this Encycl, p D38-R and under Detonation and Explosion, Development (Transition) from Deflagration or Burning (Combustion)... 

Transition from Deflagration to Detonation in Solids , 3rdONRSympDeton(I960), pp 606-34 15) S. Wachtell C.E. McKnight,... 

Fig 4 One-dimensional precursor shock mechanism of transition from deflagration to detonation in solids... 

In Section II of Macek s paper (Ref 13, pp 44-50) is discussed the "Thermal Explosion Theory . It will be discussed in our writeup separately. Section III contains "Transition from Deflagration to Detonation , which includes the "Precursor Shock in Solids (pp 50-2) discussed in our write-up separately, and other items. Section IV contains a brief description of Gap Test (pp 56-8) and of Impact Test (pp 58-60)... 

Detonation (and Explosion), Transition from Deflagration (or Combustion) to. See Detonation (and Explosion), Development (Transition) from Burning (Combustion) or Deflagration, Section 2 and A. Ma ek, ChemRevs 62, 50-52(1962) (Transition from deflagration to detonation)... 

Detonation of a gas-air mixture may occur by direct initiation of detonation by a powerful ignition source or by transition from deflagration. This transition occurs in pipelines but is most unlikely in vessels. Two useful rules are ... 

For transitions from deflagration to detonation and vice versa see p. 85. 

Primary explosives are substances which show a very rapid transition from deflagration to detonation and generate a shock-wave which makes transfer of the detonation to a (less sensitive) secondary explosive possible. Lead azide and lead styphnate are the most commonly used primary explosives today. However, the long-term use of these compounds (which contain the toxic heavy metal lead) has caused considerable lead contamination in military training grounds. Costly clean-up... 

As broad as the coverage of this symposium appears, there is much propellant chemistry which has not been included. The experimental determination of thermodynamic properties such as heats of formation and equilibrium constants as well as the calculations of theoretical performance have been presented at other symposia. The applied chemistry related to modifying polymers, and hence mechanical and burning properties of solids, have other forums. The actual firing of solid motors and determination of thrust and efficiency have been omitted while the research into combustion instability and the transition from deflagration to detonation are only alluded to. 

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