Three-dimensional numerical simulation for hydrogen/air detonation: Rectangular and diagonal structures

Abstract

Unsteady three-dimensional simulations of hydrogen/air detonations in a rectangular tube have been performed using a detailed chemical kinetics model to reveal its structure. The simulations clearly show detailed three-dimensional detonation modes, namely a rectangular mode and a diagonal mode. The rectangular modes that were obtained are of two types: in phase and partially out of phase. These rectangular modes consist of two two-dimensional waves, and the cell length for these modes is approximately the same as in two-dimensional simulations. The diagonal mode is shown to result from three-dimensional diagonal motion of the triple-point lines. The cell length of the diagonal mode is about three-quarters of those obtained in the two-dimensional and other three-dimensional simulations. The detonation front for both rectangular and diagonal modes adopts a complicated three-dimensional time-dependent pattern, and the results agree well with experimental observations reported by many researchers. Furthermore, formation of unreacted pockets behind the detonation is observed in the results for rectangular mode in phase. The computational results clearly capture the resulting complicated shape patterns.