Detonation structure with simplified chain-branching kinetics.

摘要

Hydrogen-oxygen chemistry is characterized by a chain-branching mechanism that yields three explosion limits. While an appropriate detailed kinetic scheme should produce correct results, in many circumstances, a simpler yet reasonably realistic model will be warranted. To that effect, a four step chain-branching scheme that exhibits an explosion behavior with three limits, very similar to hydrogen, is considered. The structure of detonation waves is focused upon using a combination between numerical simulation and analysis. Numerical simulations show distinctive keystone figures in the flow field, close to observations in hydrogen-oxygen detonation experiments. The steady wave structure is resolved using a perturbation analysis, which clarifies the differences between explosion and no-explosion regions and allows for an evaluation of the reaction length.; Detonation cell size is also a major focus in this study. The multi-dimensional linear stability of planar detonation waves for both a single step Arrhenius rate with arbitrary reaction order and the four step model are examined. A normal mode analysis with an iterative shooting method is used. Numerical simulations confirm previous numerical results that show that the most unstable transverse wavelengths from linear stability analysis are comparable with the minimum channel width in which one full cell is observed. The cell size is initially dominated by the shorter, more unstable wavelength, but eventually evolves toward the largest size consistent with both the stability spectra and the domain width.