摘要
Numerical simulation has been performed to investigate the DDT(Deflagration-to-Detonation Transition)mechanism by solving fully compressible reactive flow for hydrogen/air mixtures in tube with sudden cross-section expansion.The results reveal the acceleration action of abrupt cross-section on DDT,which is validated by comparing the run up distance and time with corresponding long annular tube and single tube.Detailed discussion of flow field variations finds that the DDT process in cross-section abrupt tube can be divided into three stages(flame acceleration,transition to detonation,and detonation propagation stages respectively)according to different flame modes.Particularly,it is found that formation of vortex could accelerate DDT by promoting turbulent mixing of hot products and cold reactants.Further comparative analysis on DDT characteristics of cross-section abrupt tube with different annular gap lengths shows that different mechanisms dominate in the single tube zone.The conclusions in present study support the cross-section abrupt tube as a means to enhance DDT and provide an alternative potential in practical pre-detonation initiator and pulse detonation engine applications.
基金
the Fundamental Research Funds for the Central Universities(Grant No.HEUCFJ170304,Grant No.HEUCFP201719)for supporting this work。
