Flame Implosion and Shock Wave Focusing Induce Detonation Initiation

摘要

Computational simulations were carried out on detonation generator of different structures to study the phenomena, mechanism and gas dynamics characteristic of flame implosion and shock wave focusing. Two-dimensional axisymmetric and unsteady Navier-Stokes equations were numerical 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 spark in the jet flame burner accelerates under the narrow channel, jet flame impinging on the axis strengthens shock wave, and shock wave enhances flame acceleration. Under the function of multiple shock waves and flame, a number of hot spots appear between the shock wave and flame surface, which enlarge rapidly and form an over-drive detonation with high pressure, which declines to stable detonation. Through calculation and analysis, the lengths of detonation initiation and stable detonation could be obtained, which would provide useful information to further experiment