https://orcid.org/0000-0002-7508-4611
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ABSTRACT
Ammonium dinitramide-based ionic liquids (ADN-EILPs) are a promising alternative to hydrazine monopropellants. Continuous wave (CW) laser heating using carbon wools is an effective approach to attain the rapid ignition of ADN-EILPs. This study aims to verify the influence of the dispersibility of carbon additives in ADN-EILPs on their ignition. The investigation was performed by performing fluorescence microscopy of samples imitating the mixture of ADN-EILPs with carbon additives and CW laser ignition tests of ADN-EILPs with several yarn-lengths of carbon wools. Based on these results, the dispersity mechanism of carbon additives in ADN-EILPs is proposed, which indicates that the use of high-power laser is not an effective approach to ignite ADN-EILPs consisting of carbon additives with high dispersibility. During sample preparation for the ignition tests, it was verified that the difference in the length of carbon yarns affects the bulk density and morphology of the prepared samples, and dispersibility of carbons. The results of the ignition tests indicate that samples whose morphology altered into a liquid-like morphology cannot be ignited and the ones who retained their original one can be ignited. The physical distribution of the residue of samples with a liquid-like morphology, observed after the ignition tests, agrees with the discussion regarding the dispersibility mechanism of carbon additives, obtained through fluorescence microscopy. Moreover, for the samples exhibiting an ignition capacity, the bulk density of additives would be crucial to be considered to achieve the effective ignition.
Acknowledgements
Fluorescence microscopic observations were supported by Mr. Masao Nagasawa of Keyence Co.Ltd. This research was supported by the JSPS KAKENHI Grant-in-Aid for JSPS Research Fellow JSPS-18J14397.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Symbols and subscripts
| Symbols | ||
| I | = | Current |
| V | = | Volume |
| λ | = | Wavelength |
| ɸ | = | Laser power |
| t | = | Time |
| c | = | Speed of light |
| T | = | Temperature |
| P | = | Pressure |
| h | = | Height |
| l | = | Length |
| x | = | Coordinate on x-axis |
| y | = | Coordinate on y-axis |
| d | = | Diameter |
| n | = | Number of experiments |
| F | = | Force |
| J | = | Energy density |
| η | = | Viscosity |
| ρ | = | Density |
| γ | = | Surface tension |
| ν | = | Kinetic viscosity |
| L | = | Characteristic length |
| Δ | = | Difference |
| β | = | Coefficient of thermal expansion |
| α | = | Thermal diffusivity |
| v | = | Velocity |
| Ma | = | Marangoni number |
| Gr | = | Grashof number |
Subscripts
| max | = | maximum |
| ef | = | effective |
| exp | = | experiments |
| laser | = | laser beam |
| rad | = | radiation pressure by laser beam |
| un | = | unit |
| L | = | liquid |
| m | = | molar |
| 0 | = | initial state |
| 1 | = | state after a certain time (Δt) spends |
| c | = | critical |
| s-210 | = | the sample named S-210 |
| s-231 | = | the sample named S-210 |
| s-241 | = | the sample named S-210 |
| 10% | = | 10% of maximum power of metal halide lamp |
| 20% | = | 20% of maximum power of metal halide lamp |
| 40% | = | 40% of maximum power of metal halide lamp |
| 100% | = | maximum power of metal halide lamp |