Numerical simulation and experimental study on flame acceleration in annular detonation duct

Numerical simulation of annular detonation duct with orifice plate of different numbers were carried out to study the phenomena of flame acceleration,the evolution of deflagration to detonation transition (DDT) and the detonation initiation distances at different equivalence ratios.Two-dimensional axisymmetric and unsteady Navier-Stokes equations were numerically simulated.The results of numerical simulation show that laminar flame is generated by low energy ignition in the region of flame mixing.The flame of low velocity jets to annular detonation duct,and propagates to the export with a changed direction.The laminar flame becomes turbulent flame in the obstruction of orifice plate and under the acceleration action of shock wave and reflected wave.The turbulent flame is strengthened mutually with its induced shock wave,and then detonates the unburned mixture.The progress of detonation propagation in the region with obstacles was also analyzed.The flame velocities and detonation initiation distances at different equivalence ratios were studied respectively.Through calculation and analysis,deep understanding of flame acceleration and DDT was obtained,and data for the mechanism of indirect initiation were accumulated.