Formation of dark zone and its temperature plateau in solid-propellant flames: A review

Modeling of combustion and ignition of solid-propellant ingredients

“…The calculated dark-zone length increases with increasing laser flux [112]. A comprehensive discussion of this subject was recently presented by Yang et al [99]. Fig.…”

“…The dark-zone temperature plateau in a solidpropellant flame is caused by a combined effect of fluid transport and high activation energies of reactions of some intermediate species, such as NO, CO, and HCN [99]. These species need a period of residence time before they can undergo vigorous exothermic reactions to form final equilibrium products (H 2 O, N 2 , CO 2 , CO, etc.).…”

“…The equilibrium flame temperatures range from $1400 K for AP to greater than 3000 K for nitramines. A dark-zone temperature plateau exists in the range of 1-50 atm for nitrate esters [99,168] and up to 40 atm for ADN [10]. GAP [128,148,169], ADN [170], and AP [93] are known to release a significant amount of energy in the condensed phase, whereas the nitramines RDX and HMX release most of their energy in the gas-phase [7,17].…”

“…Table 4 lists monopropellants that have been modeled using this paradigm. In addition to issues related to burning-rate characteristics, the existence of darkzone temperature plateaus in nitrate ester and nitramine propellant flames has been addressed [16,92,99].…”

Developing Reaction Chemistry Models from Reactive Molecular Dynamics: TATB

“…However, careful analyses of cook-off experiments have shown that multistep reaction schemes are required to model those response characteristics [5][6][7]. The modelling of propellant combustion processes (especially those containing high explosive constituents HMX and RDX) are quite generally written as containing multiple steps, which are necessary to describe the observed flame structure and its dependence on the confining pressure [8][9][10][11]. Defining the deflagration rates of such materials under moderately high pressures requires an understanding of this staged reaction process (preferably expressed in an Arrhenius form) and how temperature and pressure evolve in the flame structure [12].…”