An extension of transition-state theory for shock-induced chemical kinetics

Abstract

A qualitative chemical kinetics model is developed for shock environments based on a straight-forward extension of transition-state theory. The model assumes that the distribution of initial velocities along a reaction coordinate is centered about the projection of the shock velocity along that coordinate. The resulting model possesses several highly desirable qualitative features. The first is an adiabatic quality in which the reaction rate depends explicitly on the projected-shock velocity instead of relying on some effective temperature. The second is saturation of the shock amplification of the reaction rate at a critical projected-shock velocity related to the barrier height of the reaction. Third is that the model can act as an extrapolation guide for extending thermally-measured rate constants to a shock environment. Finally, the explicit dependence of the reaction rate on projected-shock velocity, rather than the total shock speed, imparts a natural sense of anisotropy in the shock-induced kinetics. A 1D numerical simulation supports the presence of these features in shock-induced kinetics.