Abstract:

Droplet tests were performed to study the hypergolic ignition characteristics of three imidazolium dicyanamide ionic liquids blending with different proportions of furfuryl alcohol. Two high-speed cameras and an infrared camera were used to synchronously obtain macroscopic, microscopic, and infrared images of the fuel hypergolic process. The coalescence and reaction process of droplets and liquid pools beneath the liquid surface was also captured. A typical three-stage hypergolic process was observed in the experiments: spreading and mixing, gas-phase products generation, and occurrence of flame kernel and flame propagation. Ignition delay time was defined to quantitatively characterize the hypergolic reactivity. The results showed that the addition of furfuryl alcohol can effectively reduce the viscosity of the fuel blends, promoting the mixing of fuel and oxidant, accelerating the emergence of high-temperature gas-phase and foggy products. The ignition delay time of the mixed fuel changes non-monotonically with the addition ratio of furfuryl alcohol. The blending ratio with the shortest ignition delay increases with the increase of droplet speed; the propulsion performance of the mixed fuel is less affected by the addition of furfuryl alcohol. This research can be a valuable reference for the development and utilization of hypergolic ionic liquid propellants.

Key words: ionic liquid, furfuryl alcohol, hypergolic, ignition delay time, specific impulse, viscosity, fuel

摘要：

利用落滴法对比了三种咪唑二氰胺离子液体分别掺混糠醇的自燃特性，使用高速摄相机和红外摄相机同步获得了燃料自燃过程的宏观、微观及红外图像；从液面下方拍摄了液滴与液池的混合反应过程。实验观察到了典型的三阶段自燃现象：铺展混合、气相产物生成及火核出现-火焰传播，使用着火延迟时间对燃料的自燃活性进行了定量表征，并计算了糠醇比例对混合燃料推进性能的影响。结果表明，糠醇添加可以显著降低混合燃料黏度，促进燃料与氧化剂的混合，加速自燃过程高温气雾产物的出现。混合燃料的着火延迟时间随糠醇添加比例非单调变化，着火延迟最短的掺混比随液滴速度的增加而增大；混合燃料推进性能受糠醇添加的影响较小。本研究可为自燃离子液体推进剂的开发及利用提供参考。

关键词: 离子液体, 糠醇, 自燃, 着火延迟时间, 比冲, 黏度, 燃料