Detonation Wave Structure of Gases at Elevated Initial Pressures

ABSTRACT

The characteristic “structure” of gaseous detonation waves, defined here as the spatial variation of the pressure, temperature, density, species concentrations, and velocity within the detonation wave is examined theoretically at elevated initial pressures. The approach taken in this work is to extend the Zel'dovich-von Neumann-Doering (ZND) theory of gas-phase detonation to use real-gas equations of state, Chemkin Real Gas, a computer program capable of calculating real-gas thermodynamic properties and chemical kinetic reaction rates, is used to describe the P-V-T behaviour of the gaseous mixtures in this investigation. The mathematical model for a ZND detonation wave is presented in an equation of state independent form and integrated numerically for a hydrogen-oxygen system to determine the structure of the detonation wave. The ZND model is used to characterize the thermodynamic states and reaction zone length scales present in the detonation wave. The variation of the reaction zone length parameters is examined as a function of the initial pressure, temperature, and composition. The distance from the shock front to the maximum temperature derivative is shown to be a reproducible reference location in the detonation wave structure. The numerical calculations exhibit sensitivity to equation of state dependent constants and pre-exponential rate coefficients in the elementary reaction mechanism.