Three-dimensional detonation structure and its response to confinement

Abstract

Three-dimensional (3D) detonation simulations solving the compressible Navier-Stokes equations with detailed chemistry are performed in both square channel and round tube geometries. The simulations are compared with each other and with two-dimensional (2D) channel simulations and round tube experiments of identical mixture and conditions (stoichiometric hydrogen-oxygen with 3000 PPMv ozone at 300 K and 15 kPa) with the goal of understanding the effect of confinement and boundaries on detonation structure. Results show that 3D detonations propagate with highly inhomogeneous blast dynamics, where blasts emerge not only from intersections of two transverse waves (similar to 2D propagation) but also from intersections of many transverse waves (unique to 3D detonations in the confinements tested). Intersections of many transverse waves lead to extreme thermodynamic states and highly overdriven wave velocities, well in excess of those seen in the ZND model and in 2D simulations. 3D simulations in the square tube show highly regular blast latticing, smaller detonation cells, and highly oscillatory velocities when compared to the round tube simulations. Round tube simulations show more spatially non-uniform blast dynamics. The conclusions reached in the current work are found irrespective of numerical grid resolution.