A two-phase mixture theory for the deflagration-to-detonation transition (ddt) in reactive granular materials

Modeling of shock development and transition to detonation initiated by burning in porous propellant beds

An analysis of the transient reactive flow through highly loaded but mobile particles of solid propeliant is presented in order to determine whether the high-speed flame front can provide a pressure wave that can interact with the flow to build up to a condition of detonation. Discussions are presented which deal with the various forms of the field balance conservation equations, as well as the significant number of additional constitutive relations required to model this flow. Results are presented which indicate the sensitivity of the most important parameters on the unsteady flame-spreading rate. Possible criteria for DOT (deflagration-to-detonation transition) are presented.

Modeling of Convective Mode Combustion through Granulated Propellant to Predict Detonation Transition

Hazard initiation in solid rocket and gun propellants and explosives

Introduction T HE deflagration-to-detonation transition (DDT) in solid energetic materials has been of interest to researchers for many decades since it has a variety of areas of applicability, ranging from industrial to military. A recent example of the former is the detonation that occurred during the production of propelling charges for hunting ammunition. In the military area, the applicability extends from gun systems and projectile impact hazards to rocket motors. Hence, the DDT process has been investigated for both voidless (cast) and porous systems. We shall use the rocket motor environment to assess the DDT hazards associated with high-energy propellants. In the area of solid propellant rocket motors, an oft-asked question is "Will a cast, well-manufactured rocket propellant grain undergo a transition to detonation from the burning mode?" The answer is no, to the best of our knowledge. Although there are few journal articles directly providing this assessment, our knowledge of the DDT mechanism in gases, liquids, and solids provides a rationale for reaching this conclusion. The rationale is based on the thesis that the deflagration process must ultimately produce a shock wave to drive the system to detonation.' That is, the shock-to-detonation transition (SDT) is the final stage in any DDT process. Consequently, in the solid-propellant rocket motor situation, the confinement provided by the motor case must be sufficient to allow the pressure from deflagration to build up to a sufficiently high shock pressure to initiate the cast propellant. As will be shown below, these shock amplitudes cannot be reached for cast propellant systems confined in rocket motor cases.

B. D. Hopkins

Papers

Convective combustion modeling applied to deflagration-to-detonation transition of HMX