双元液滴MEA-NaBH4与H2O2自燃点火特性:偏心碰撞的影响OA

In this study,hypergolic ignition of hydrogen peroxide(H2O2)and monoethanolamine-so-dium borohydride(MEA-NaBH4)by off-center collision of their droplets was experimentally studied.The pictures of the collision ignition process were obtained by a high-speed camera.The characteristics and physical mechanisms of droplet mixing,droplet heating and evaporation,and gas phase ignition process were mainly explored.Compared with the central collision ignition process,the off-center col-lision ignition process can also be divided into five stages.When Bias(B)<0.35,it is observed that the H2O2 droplets after collision will penetrate the MEA-NaBH4 droplets and coalesce with them.Due to the existence of angular momentum,it will not form a stable sphere under the condition of central collision,but expand and ignite after internal rotation and stretching.When B increases to 0.59,the droplets after the collision separate to form one or more micro-satellite droplets,and a multi-ignition mode is observed.As the B value increases to 0.85,a rebound collision of droplets is observed.At this time,although the droplets interact with each other,there is no mass transfer process,resulting in ignition failure.The experimental results show that the droplet ignition delay time decreases linear-ly with B under different Weber number(We),and finally decreases to the same minimum value and remains unchanged.In addition,this study continues the previous work,using a theoretical model to quantify the droplet expansion rate to calculate the volume change of the droplet.By comparing with the experimental results,it is found that the droplet expansion can be attributed to the flash evapora-tion of superheated H2O2 inside the mixed droplet.Finally,the ignition mode mechanism diagram corresponding to different droplet mixing characteristics in the We-B parameter space is established.