Laser ignition on single droplet characteristics of aviation kerosene at different pressures and initial diameters: ignition, combustion and micro-explosion

In this study, an experimental system for single-droplet ignition by laser under different pressures is established, and the laser ignition is used to examine how pressure and initial diameter influence ignition properties of RP-3 aviation kerosene single-droplet. The findings reveal that depending on the extent of the impact of bubble rupture on the droplet's shape, The droplet's morphological alterations can be classified into three types: micro-expansion, puffing, and micro-explosion. The ignition and combustion of droplets is segmented into four distinct phases: heating, ignition, intense combustion, boiling combustion. The flame width diminishes with rising pressure. Single droplet ignition delay time is strongly influenced by the pressure, which is reduced by 92.7 %, 94.1 % and 94.3 % for the three droplets from small to large diameters with the pressure increases from 1 bar to 4 bar. The change trends of droplet diameters are first increasing and then decreasing. The whole burning rate of RP-3 droplets goes up with the rise of pressure. A droplet laser ignition model is proposed, the minimum ignition energy of RP-3 droplets with an initial diameter of 1.42 mm at pressures of 1–4 bar are obtained to be 0.88 J, 0.80 J, 0.68 J, and 0.59 J, respectively.