Numerical simulation of detonation initiation in a duct via imploding annular detonation

Computational simulations on detonation duct with different annular pre-detonators were carried out to study the phenomena,mechanism and gas dynamics characteristic of annular detonation initiation.Two-dimensional axisymmetric and unsteady Navier-Stokes equations were numerically simulated,and detailed chemical reaction kinetics of hydrogen/air mixture was used.The results of numerical simulation show that laminar flame generated by low energy ignition in annular pre-detonator accelerates under the narrow channel,and then forms annular detonation via deflagration to detonation transition.Annular detonation detonates the combustible mixture in the main detonation chamber after reflection and imploding at the axis.Contrastive research on the distance and intensity of stable detonation was analyzed.Through calculation and analysis,it provided a deep understanding on the aerodynamics characteristic of annular detonation wave diffraction,reflection and imploding and the development of complex wave in the transitional region,laying a theory basis for detonation initiation and useful information to further experiment.