Publication Date: 2016 Venue: Salt Lake City, UT Domain: Space and Aeronautics
Certain types of ionic liquids have shown energetic properties in combination with select oxidizers. Due to their low vapor pressure and hydrolytic stability, these substances have become increasingly attractive as hydrazine replacements for space propulsion applications. This study aims to understand the hypergolic nature of a few ionic liquids by characterizing the ignition delay of their reaction with white fuming nitric acid (WFNA).
Two ionic liquids were synthesized for this study: 1-butyl-3-methylimidazolium dicyanamide ([BMIm][DCA]) and 1-butyl-1-methylpyrrolidinium dicyanamide ([BMPy][DCA]). A fuel additive, trimethylamine borohydride (TEA*BH3) was also tested in combination with the ionic liquids. Results show that the ionic liquids synthesized, which needed more purification to eliminate some residual water, provide ignition delays of around 70-80 ms. Those with the fuel additive performed significantly better with ignition delays closer to 10 ms.
Heats of formation were also calculated computationally to be used for determination of specific impulse (Isp) and characteristic exhaust velocity (C*) for better comparison of the projected performance of these fuels. These metrics show that these combinations can provide comparable, but lower, performance characteristics compared to hydrazine and monomethylhydrazine (MMH) monopropellant and bipropellant regimes.