Abstract

When a cellular detonation propagates in a tube with rough-wall boundary conditions, its propagating velocity becomes less than the ideal Chapman-Jouguet (CJ) value due to losses. In addition, the intrinsic cellular pattern of this quasi-detonation and its reacting flow fields can be strongly changed by the presence of wall roughness. This study aims to clarify the wall boundary effect by investigating the quasi-detonations under different degrees of wall roughness defined by various characteristic factors. A computational analysis is conducted using two-dimensional numerical simulations. The governing equations are given by the reactive Euler equations with a two-step Arrhenius induction-reaction kinetic model and solved numerically using a second order finite-volume scheme with Graphics Processing Unit (GPU) computing. A parametric study is reported by varying the channel width, obstacle size, obstacle spacing and chemical reaction parameters, to investigate perturbations created by the rough wall to the intrinsic cellular detonation instability and eventually the detonation failure or propagation limit. Apart from the numerical smoked foils to reveal the dynamic evolution and irregularity of cellular detonation patterns, the degree of instabilities caused by the roughness is analyzed by looking at the probability density function of the pressure and induction rate from the detonation flow fields.