2ème atelier international
J. Phys. IV France 05 (1995) C4-309-C4-330
A New Kinetics and the Simplicity of DetonationF.E. Walker
Interplay, Danville, California, U.S.A.
The results are presented from three experiments, as well as a number of molecular dynamics and quantum mechanics calculations, which cast in serious doubt the validity of some concepts and theories of detonation. This doubt led to numerous studies in search of more satisfying concepts, and the quite surprising results of several of those studies are given. Particularly, a new concept of the kinetics of shock-induced chemical reaction is presented. This process, designated as physical kinetics, is described as a nonequilibrium, nonthermal process in which chemical reaction rates are determined and regulated by the averaged vibrational velocities of the bonded atoms in condensed systems under the influence of high velocity shock waves. These velocities limit the advance of the kinetic energy which leads to the very high impact velocities of the atoms and molecules which cause massive bond fracture in the molecules in extremely short times. The majority of the free atoms and radicals and other highly activated species formed then react in very short times (10-14 to 10-12 s), often in chain reactions, to provide the chemical energy which maintains the enormous level of kinetic energy at the detonation front. These high levels ensure that many reaction path-ways are available--not only those with the lower activation energies or barrier potentials. It is in this regime of the detonation process that the more normal chemistry begins and then continues in other subsequent reactions to produce the adiabatic expansion forces and the final product mixtures. It is shown that this detonation model based on the new kinetics model, with the major initial reactions occurring in times of the order of tenths of picoseconds and in distances on the order of tens of angstroms--in the shock or detonation front--can provide a precise and satisfying mathematical and physical description of detonation phenomena.
© EDP Sciences 1995