Effect of Diffusion Time on Deflagration and Detonation Parameters of Ethene-Air

A vertical shock tube of 200 mm in inner diameter and 5 400 mm in height was used to study the deflagration and detonation parameters of ethane-air mixtures under a high initial pressure(0.25 MPa).The gas mixtures flow into the shock tube through two inlets at two ends of the shock tube instantaneously, the experiments of 3 concentrations of mixtures and 5 diffusion times were carried out with high initiation energy.The experimental results show:when the diffusion time exceeds 1 h, the trends of the deflagration-detonation parameters of C₂H₄-Air for 3 concentration are similar; 4.00%(volume fraction)C₂H₄-Air can't meet the detonation criteria under the experiment condition; 6.67%C₂H₄-Air can be ignited at 5 diffusion times, the detonation pressure and velocity separately are 4.24 MPa and 1 719 m/s when the diffusion time is 1 h; 8.89% C₂H₄-Air deflagrates when the diffusion time is 0.08 h, the detonation pressure and velocity separately are 4.31 MPa and 1 813 m/s when the diffusion time is 1 h; We seized the detonation cell size of 6.67%, 8.89%C₂H₄-Air by smoked foil, the width separately are 8.22 and 14.15 mm, L/λ separately are 1.44 and 1.57.