Deflagration to detonation transition process in aluminum dust-air mixture

Ignition, flame acceleration and deflagration to detonation transition in fine flake aluminum dust-air mixture under weak ignition of 40J was studied in a horizontal tube with an inner diameter of 199 mm and length of 29.6 m and equiped with 40 sets of special dust dispersion system. The influences of aluminum dust concentration and ignition delay time on the deflagration to detonation transition(DDT) process of aluminum dust-air mixture were discussed. The experimental results show that the whole DDT process of aluminum dust-air mixture can be divided into slow reaction compression stage and fast reaction shock stage. With the ignition delay time of 370ms and aluminum dust concentration of 300g · m^-3, the dimensionless transition distance from ignition point to the detonation wave formed in aluminum dust-air mixture is 83 times L/D ratio, and detonation occurs with a peak overpressure of 9.8MPa and velocity of 1670m · s^-1. Self-sustained detonation wave of aluminum dust-air mixture is characterized by the existence of spin detonation structure. The front wave velocity and overpressure of self-sustained aluminum dust-air mixture oscillate with the propagation distance.