铝粉-空气混合物的燃烧转爆轰过程

利用自行设计的长29.6 m、内径199 mm配有40套喷粉扬尘装置的大型水平爆轰管,研究了细片状铝粉-空气混合物在40 J弱点火条件下火焰从发生到加速、最后实现爆轰转捩的全过程,探讨了铝粉浓度和点火延迟时间对爆轰参数的影响.结果表明,铝粉-空气混合物燃烧转爆轰(DDT)过程可分为慢速反应压缩阶段和快速反应冲击阶段.当点火延迟时间为370 ms,铝粉质量浓度为300 g/m~3时,在管道中距离点火位置83倍长径比处峰值超压为9.8 MPa,爆速为1 670 m/s,发生了DDT过程.在铝粉-空气混合物自持爆轰波的传播过程中,由于呈现螺旋爆轰波结构,爆速和峰值超压随着传播距离振荡.

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 40 J 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 370 ms and aluminum dust concentration of 300 g·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 9.8 MPa and velocity of 1 670 m·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.